~ Author: Chloe Wong, 12-year old rock enthusiast

Many people, including myself, are terrified of lightning. I mean, the sudden loud ”BAAAM” can really scare me sia 🙁
But there are some instances where lightning isn’t scary at all, where the sudden strike of lightning does not make you jump up like its a jump scare, when the lightning has already struck.

Fulgurites, in other words, Petrified Lightning, are the less-scary aftermath of when lightning strikes the ground. Fulgurites are derived from the word ”Fulgur”, meaning lightning in Latin. When lightning strikes and discharges into the ground, it fuses and vitrifies with the soil, sand, rocks,organic debris, mineral grains or other sediments into a glassy silica mineral. Fulgurites, therefore can be classified as Petrified Lightning.

The most common type of fulgurites are sand fulgurites, formed when lightning at a temperature beyond 1,800 degrees strikes on silica-rich sandy beaches. Some fulgurites are formed from ancient lightning that struck even before our parents were born, but to find those it’ll take a lot of labour, who knows where they are buried deep in the sand. Just imagine Thor striking a beach with lightning from his hammer, there would be so many fulgurites left on the beach 🙂

Fulgurite captures the shape of the lightning bolt when it disperses into the ground. No two lightning strikes can look the same. Each fulgurite mimics different and unique shapes and patterns of its lightning bolt. Kind of like us actually, we’re all unique in our own way, we can’t be perfect. I think this is the only type of lightning I find friendly, I mean it doesn’t make a lot of noise am I right?

A twelve-year old’s passion for rocks

Hi everyone, I’m Chloe. 🙂 . I just finished my PSLE exams and gotten my results, yea! Pretty happy with my grades after working hard and just hoping that I will get into the school I’ve applied for in the coming new year. I’m going to be sharing how a twelve-year old started a passion, for an unusual subject – rocks & minerals!

The first thing that may come to your mind is, ”Why rocks?” Little do you know that there is a whole other world surrounding them, a world that not everyone has seen, how Mother Nature has put them on this earth, for us to unravel their beauty, their hidden beauty.

Around the time when I was four-years old, my parents bought all three of their children each a necklace, each holding a different type of gemstone for all three of us. My sister had a clear quartz, my brother a tiger’s eye, and I had one of the most common gemstones – amethyst. The moment I wore it, I knew I was going to have a certain relationship with it. I wore it everywhere I went, I even wore it to kindergarten!( even when i wasn’t allowed to ) I remember how I would hold it up to my eye and look at its amazing purple colour, and its inclusions inside of it would make it look like a landscape ( especially since purple is my favourite colour ) . It helped me calm my nerves and kept me at a peaceful state when I looked at it, even when my parents were fighting.

When I started Primary school, I started focusing more on exams and tried my hardest to to be best in my classes, and most of all make friends. I stopped wearing my necklace and completely forgotten where it was. I did work hard, but I felt like something was missing.

After four years of primary school, my family went through some changes and we had to move house. As I was unboxing the boxes in our new house, I found one of the most precious thing to me. The necklace still fits perfectly around my neck even without adjusting the size at all for four years. When I found it, I remembered the times I spent wearing it around with me as a kid. I realized that I had a passion for gemstones and did my research on everything about them.

During my research, I noticed that alot of people mistreat or misuse them. We can’t expect them to make our problems go away or give us superpowers just by holding them. They are on this earth for us to appreciate them, not to use them as a tool. That’s how I discovered The Gem Museum, I learnt that I can chase my dream and that I can pursue my passion at this place. I decided to spend my holiday in a meaningful way to be at The Gem Museum to learn all I can and be with people that share the same passion! I know there are other twelve-year olds out there that don’t know what their passions are, I encourage you not to give up on finding it no matter how long it takes. 🙂

Good luck 🙂

Chloe Wong, the rock enthusiast.

Here I am, at the Rock Garden corner of The Gem Museum!
Reunited with my most precious amethyst necklace!


  •  作者:陆荟颖,宝石博物馆创办人



  • 美丽
  • 稀有性
  • 耐久性



  • 需求


例如,在亚洲文化中,我们重视帝王翡翠玉。 98%的翡翠玉是在缅甸的一个矿区Pharkant生产的。由于帝王绿品质非常罕见,供应很难满足需求。因此,这种物质备受追捧。


另一个例子是钻石。 “钻石是女生最好的朋友。”戴比尔斯(De Beers)的这个口号已经大大推广了钻石在订婚戒指中的使用,以至于它对钻石产生了不断增长的需求。



  • 传统


crown jewels


proposal ring
  • 便携性






所以现在我们可以看到便携性如何影响宝石的价值!事实上,由于这个因素,宝石被认为是能保持价值又非常好的 “投资” 商品!


了解这6个因素可以帮助你以实际的方式了解宝石的价值。 在本系列的第3部分中,我们将与你分享一些你可以做的事情,来取得市场经验。

Assessing Value of Gems (Part 2)

3 More Gems Factors

The first 3 factors to understand and consider before you begin to assess the value of the gems are:

  • Beauty
  • Rarity
  • Durability

Read about the first 3 factors here!


Value of Gems

  • Demand

Because of the beauty and rarity of gemstones, there is a demand. In different cultures, there is a demand for different variety of gems.

For example, in the Asian culture, we value the imperial green jadeite-jade. 98% of jadeite-jade is produced in one mine in Myanmar, Pharkant. As the imperial green quality is very rare, the supply is hard to meet the demand. Hence, this material is highly sought after.


Green Imperial Jadeite-jade is very sought after. One way to give more value to a piece of jewellery, yet still affordable, is to use smaller pieces of high quality jade.


Another example is diamond. “Diamonds are a girls’ best friend.” This slogan by the marketing agency of De Beers has popularized the use of diamond in an engagement ring so much that it created an in-flux of demand for diamonds.

2 oval yellow diamonds with 1.50ct D colour Diamond set in 18K white gold.

High quality diamonds like a 5 carat, D colour, Internally Flawless and excellent cut piece is rare and hard to come by.



  • Tradition

The royal crown jewels are an important set of jewellery because it tells the history of a nation. The royalties are an icon to the nation and perhaps even a role example for others around the world.

crown jewels
Imperial State Crown, UK Photo Source: https://en.wikipedia.org/wiki/Crown_Jewels_of_the_United_Kingdom

When Prince William and Prince Harry got married, the trend of using a blue sapphire and aquamarine for an engagement ring went up tremendously. During these seasons, the demand increased. Some quality-grades of the gems were very difficult to get too.


proposal ring
Emerald cut aquamarine from Afghanistan. Prince Harry’s wife, Megan Markle received an aquamarine ring for proposal.


  • Portability

This is an interesting factor. Portability can also be understood as “transportability”. Gemstones are small and lightweight. It is even better when set into a piece of jewellery. One can wear it and travel around the world (with insurance of course!).

24 carat Colombian Emerald worth USD120,000 can be worn from one place to another.

One of the stories that we have heard from our Director, Mr. Tay Thye Sun, happened in 1997. It was during the Asian financial crisis. A lady from Indonesia who looked really normal and unnoticed came into his gem testing laboratory.

She look a piece of diamond for testing and evaluation and found that it was about USD5000 at that time. She then went on to test another diamond of about 1 carat in weight. This diamond was evaluated to be worth about USD15,000 at that time.

The next thing we know, she took out a small pouch and poured out all the diamonds in that pouch. All in all, the diamonds in that small little pouch was worth a few million dollars (there were 5 carat diamonds too).

So now we can see how portability can affect the value of gems! In fact, gemstones are seen to be very good commodities to “invest” in to keep value because of this factor!


In Conclusion…

Knowing these 6 factors can then help you to understand the value of gems in a practical manner. In the 3rd part of this series, we will share with you some practical things you can do to gain market experience.

评估宝石的价值 (第一部分)



天然的宝石和矿石 (当然也包括珠宝!)是美丽,迷人又稀少的。我们知道它们有一定的价值,也都是人人想拥有的。



在这三部分评估宝石价值的系列,我们不会展示到底怎样来评估宝石价值的细节。但我们要让你见识到在你开始评估宝石的价值之前, 所需要了解和考虑的因素。



  • 美丽
  • 稀有性
  • 耐久性
  • 需求
  • 传统
  • 便携性



Assessing value of gems
一套用于颜色比较的蓝宝石。在评估宝石价值时, 颜色是一个重要因素。


稀有是指罕见或不寻常。钻石稀有是因为采矿的产量很低。每开采5克拉钻石, 需要加工约300吨的矿石。同样的, 对于红宝石和蓝宝石, 在许多采矿国家, 采矿技术仍然非常手工, 尽管有些是半自动的。例如, 克什米尔蓝宝石是在非常恶劣的条件下开采的。因此, 解释它的稀有性。

由于其惊人的光学效果,使那类的宝石罕稀少。为了达到完美的猫眼效应 (猫眼) 或星光 (星形), 它取决于粗糙的原料以及宝石雕琢的技术。当最好的这两个元素凑在一起,那雕琢出来的宝石就变得很稀有。

assessing value of afghanistan emeralds




耐久性涉及几个因素:硬度,韧性和稳定性 (当接触到光,热和化学)。我们将在接下来的博客文章中讨论这些内容。


assessing value by duarbility




Can inclusions or “flaws” in the gemstone tell you anything?

Inclusions contain important information about the gemstone and the natural history of our earth! Of course, most people that are familiar with diamonds would say, the more inclusions the diamond has the lower the quality. In grading gemstones, we are more forgiving in terms of clarity grading (here a brief article to explain it, https://www.gemsociety.org/article/colored-stone-grading-system/).

In this video, we would find out more about emeralds from Colombia! Those so called “flaws” that some people refer to are actually precious inclusions that tell so much about the gemstone! In the 4th stage of the mine to market story, a gemologist would examine the gemstone, test the physical properties and try to give the gemstone an identity (what gem it is), whether it has been treated and if possible where exactly or generally the gemstone is from (origin determination, one important mine for colombian emeralds is the Muzo mine http://www.muzo.co/en/millennial-legacy/muzo).

From an identification perspective, inclusions give you alot of information, from a valuation perspective it can add tremendous value if it does not affect the physical beauty of the gemstone, especially if the gemstone is from a renowned mine like Muzo for Colombian emeralds.

The moment you look at gemstones through a microscope, you will suddenly realise that there is a world of its own in the gemstone. Sometimes, these internal characteristics look to me like a snap shot of time, a snap shot of how the gemstone formed, a work of art and wonder.

You can watch this video to see some inclusions that are characteristic to Colombian Emeralds.

Featured in this video is the book called Photo Atlas by Dr E J Gubelin and Dr J I Koivula (you can get it at https://rubin-and-son.com/products_list.php?category_id=713). It contains photographs and explanation of many different inclusions in gemstones such as ruby, sapphire, emerald, alexandrite, fluorite, the list goes on.

Visit Far East Gemological Institute to start your gemology journey with our 1 day courses https://fareastgem.institute/courses/1-day-courses/

Gemstones that form in the Earth’s mantle

Only two gemstones form in the Earth’s mantle

diamonds can be found in the earth's mantle

Yellow Diamond from South Africa, a country known for its diamond mines. 

(Photo by Eric Nathan/Alamy, taken from National Geographic)


Together with diamonds, peridots are also found in the earth's mantleOlivine (Peridot) at the Natural History Museum, London.

(Photo by Aram Dulyan, via Wikimedia Commons, taken from International Gem Society)


Most gemstones form in the Earth’s crust. Only two gemstones form in the Earth’s mantle – the diamond and the peridot. These are gems that crystallise at extremely high temperatures.

 Fun fact: Diamonds may actually be the most plentiful crystals in the earth, but they just aren’t the easiest to reach

Diamonds are formed in the earth’s mantle.

Diamonds crystallise in very hot and fluid magma about 110 to 150 miles (117 to 241 kilometres) below the Earth’s surface. Because of the heat and fluidity, this magma is able to force a pathway up through the Earth’s crust at greater speeds and violence than other volcanic eruptions! These are called “kimberlite pipes”.

A simplified diagram of kimberlite pipe in earth's mantle and surface

  1. Magma pocket comes in contact with a weak area in crust.
  2. A quick explosion results, carrying diamond-bearing magma from the lower mantle to the surface. During the eruption, a cone builds on surface.
  3. The pipe eventually cools, leaving carrot shaped pipe.
  4. The cone quickly erodes away, leaving the diamond-bearing rocks where people can reach them.

(Diagram and description taken from International Gem Society)


If the rising of magma were any slower, the diamonds would likely not survive, as the changing temperatures and pressure would likely have caused them to vaporise or recrystallise as graphite.

This video shows a simple set up at The Gem Museum. It shows the formation and mining of diamonds in the world.


Geologists believe that peridot first crystallises on rocks floating in the mantle about 20 to 25 miles (32 to 89 kilometres) below the Earth’s surface. Then an explosive eruption brings them near the Earth’s surface, and weathering and erosion brings them close enough to be mined and found.


Earth's mantle forms peridots
Peridot crystal from Pakistan (The Gem Museum)


peridot forms in earth's mantle
Peridot crystals from Lisu Village, North Myanmar. (The Gem Museum)

References / Further reading:

Gem formation – International Gem Society

Where did those gemstones come from – ThermoFisher Scientific

The Rock Cycle

The Rock Cycle


rock cycle diagram

All rocks are made up of minerals. The rock cycle explains the process.

A mineral is defined as a naturally occurring, crystalline solid of definite chemical composition and a characteristic crystal structure.

A rock is any naturally formed, nonliving, firm, and coherent aggregate mass of solid matter that constitutes part of a planet.

(Diagram and description taken from Idaho Museum of Natural History)


rock cycle diagram

(Diagram from Infohow.org)


Igneous rock

Igneous rock is formed when magma from the mantle rises up through the Earth’s crust, and cools and solidifies; or when lava on the Earth’s surface cools and solidifies. Igneous rocks are primarily created with heat.

Found in igneous rock: The quartzes (including amethyst, citrine and ametrine), the garnets, moonstone, apatite, diamond, spinel, tanzanite, tourmaline, topaz and zircon.

Rock crystal (quartz) cut like diamonds.


Metamorphic rock

Metamorphic rock is formed when intense underground heat or pressure alters the existing atomic structures of minerals within rocks, and transforms them into other minerals. In essence, metamorphic rocks are created when heat and pressure change existing minerals into something new.

Found in Metamorphic rock: The beryls (emerald, morganite and aquamarine), jade, lapis lazuli, turquoise, spinel, ruby, sapphire, alexandrite, chrysoberyl and zircon.

0.77ct Ruby
0.77ct Ruby Madagascar
1.41ct Emerald
1.41ct Emerald Zambia
0.63ct Aquamarine
0.63ct Aquamarine
2.01ct Pink Sapphire
2.01ct Pink Sapphire
0.40ct Alexandrite
0.40ct Alexandrite
1.81ct Chrysoberyl Cat's Eye
1.81ct Chrysoberyl Cat’s Eye

Sedimentary rock

Sedimentary rock is formed when rock is worn down and the fragments are carried by water or the wind, and these sediments are finally compressed together over time.

Found in Sedimentary rock: Jasper, malachite, opal and zircon


The Gem Museum presents The Rock Cycle

rock cycle
The Rock Cycle set up at The Gem Musuem


The Gem Museum is set up to educate visitors on the story of “Mine to Market”. The very beginning of understanding gemstones is to learn about the rock cycle that is a very essential part of the formation of gemstones.

Come and visit us if you are in Singapore! We are opened Monday to Friday, 12pm to 5pm. Admission is free!


References / Further reading:

The Rock Cycle – 34 Kiwis

What is the Rock Cycle? – Idaho Museum of Natural History

Gem formation – International Gem Society

Where did those gemstones come from – ThermoFisher Scientific

Gemstone Formation in Earth’s Crust

Gemstone in Earth’s Crust

A raw crystal held up to the sunlight, Spinel surrounded by corundum (Vietnam).



Twin Spinel gemstone
Looking at a piece of twin spinel, Northern Vietnam.





LEFT: Alexandrite cut and polished. | RIGHT: Alexandrite in the rough.

(Photos from Gemological Institute of America)




LEFT: Sapphire cut and polished. | RIGHT: Sapphire in the rough.

(Photos from Gemological Institute of America)



emerald gemstone → 


LEFT: Emerald cut and polished. | RIGHT: Emerald in the rough.

(Photos from Gemological Institute of America)





LEFT: Ruby cut and polished. | RIGHT: Ruby in the rough.

(Photos from Gemological Institute of America)


Coco Chanel wanted to “cover women with constellations”. Like stars that pattern the night with light, jewels adorn the woman. But before being fashioned into jewellery, a gemstone is usually first a mineral (a naturally-occurring, inorganic solid with a definite chemical composition and an ordered atomic arrangement) formed by geological processes in the Earth’s crust.


Emeralds, for instance, are formed of the mineral Beryl, a chemical compound containing beryllium, aluminium, silicon and oxygen. Its colour comes from additional traces of chromium and vanadium, but different trace elements will produce different colours, allowing the mineral Beryl to form semi-precious stones such as Aquamarine.  


Rubies are formed of the mineral Corundum, and its red colour comes from traces of chromium. Sapphires are also formed of Corundum, and can come in different colours depending on its trace mixtures of iron, titanium, and chromium.


A single rock can be composed of different minerals. From rocks, mineral crystals are mined, cut and polished into precious or semiprecious gems.


How do minerals form in the Earth?

The International Gem Society has a very comprehensive article on how minerals form. In summary, minerals crystallise when conditions of temperature (heat), pressure and time to grow are right, and when there is space to grow.


Heat and Pressure determine the type of mineral formed.

Some minerals (such as Quartz – below left) require very little heat and pressure to form, and will melt or break down under great heat and pressure.

Other minerals (such as Pyrite– below right) need a lot of heat and pressure to form, because at low temperatures, its raw materials can stay mixed up with other minerals’ raw materials.

(Photo from American Museum of Natural History)


How large a crystal you get is affected by Time.

The more time there is for the crystal to grow, the larger it will be, because minerals have an ordered atomic arrangement and it takes time for atoms to be ordered. Since ions are more mobile in water, the presence of water can help accelerate the mineral growing process.


The earth is like a beautiful bride who needs no manmade jewels to heighten her loveliness.  – Kahlil Gibran


(Rock Cycle Diagram from The Geological Society)

There are 4 main processes by which gems form

(Information from the International Gem Society):

  • Molten rock & associated fluids
  • Metamorphism
  • Surface water
  • Gems formed in the earth’s mantle


Molten rock & associated fluids

(Magma crystallisation, Gas crystallisation, Hydrothermal, Pegmatites)

Lava spews out of a fissure in the Virunga mountains

(Photo by Chris Johns, taken from National Geographic)

A river of molten lava

(Photo by Carsten Peter, taken from National Geographic)


Magma crystallisation

Most minerals found in the rocks around us are formed when molten rock (or magma) rises up through the Earth’s crust due to volcanic eruptions or by heat currents that keep the magma in constant motion.


As the hot magma cools, minerals crystallise.

    • If the cooling process is extremely rapid (seconds), no crystals will form, resulting in volcanic glass (not composed of minerals). However, over millions of years, the volcanic glass may crystallise.
    • If the cooling process is rapid (minutes, hours, days, or years), the components of the minerals will not have time to be ordered, and the crystals formed will be small (less than 1mm), resulting in a fine-grained rock.
    • If the cooling process is slow (decades to millions of years), the crystals formed will be large.


During a volcanic eruption, when there is a rapid drop in pressure, gas bubbles can form in the rising magma (Imagine popping a cork from a champagne bottle.) Sometimes these gas bubbles contain a high concentration of certain elements. If the right conditions of heat, pressure and time exist, minerals will crystallise.



When water (e.g. Rain) seeps down through the soil and meets with rising magma, hydrothermal fluids are formed. Such hydrothermal fluids continue flowing through fractures in the Earth’s crust, dissolving minerals along the way. When these mineral-rich hydrothermal fluids cool in “veins” and the right conditions of heat, pressure and time exist, minerals will crystallise.



When volatile-rich magma cools in cavities and the right conditions of heat, pressure and time exist, minerals will crystallise.


Metamorphism – when minerals form from other minerals

(Contact, Regional)

The Andes mountains, formed when the Nazca plate subducted under the South American plate

(Photo by Peter Essick, taken from National Geographic)


Contact metamorphism

When magma forces its way into an existing rock formation, the intense heat breaks down existing rocks and causes minerals to re-crystallise into more stable forms.


Regional metamorphism

Intense heat and pressure arises when tectonic plates below the Earth are shoved toward each other, forcing one on top of the other (This is how mountains form). As the temperature approaches the melting point of the rock, the minerals become unstable. Over millions of years, they change into new varieties.


Surface water

When rainwater flows through the Earth, it deposits the minerals that are dissolved in it along the way into cracks in the existing rocks. Such deposits then lead to the formation of petrified wood, fossils and new minerals.


Gems formed in the Earth’s mantle

Further underground below the Earth’s crust is the Earth’s mantle. While most gemstones form in the Earth’s crust, some gems do form in the mantle, amongst which are diamonds and peridots. Read more about how they form here.

Colourful mineral deposits in the Earth’s landscape

(Photo by Thinkstock/Corbis, taken from National Geographic)


Gypsum formations that mimic flowers found in Mammoth Cave in Kentucky

(The gypsum precipitates out of water in the cave, creating these subterranean forms over time)

(Photo by Tom Uhlman/Alamy, taken from National Geographic)


References / Further reading:

Story of a gem – Gemological institute of America

What is a gem? – University of Berkeley

What is a mineral? – Oxford University Museum of Natural History

Minerals and Gems – National Geographic

Mineral forming environments – American Museum of Natural History

Formation of minerals – BC open textbooks

FAQ Mineral formation – University of California

Gem formation – International Gem Society

Plate tectonics — National Geographic


Assessing Value of Gems (Part 1)

Assessing Value of Gems

Natural Gems and minerals (and jewellery of course!) are beautiful, intriguing and rare. We all know they hold a certain value and is something that everyone would like to own a piece.

So how do we know what value and how to value a beautiful piece of gem?

First of all, assessing value of gems requires a lot of experience. Experience can come in the form of buying and selling, or learning from the books and history of previous transactions, for example in auctions.

In this 3-part series of assessing value of gems, we will not be showing exactly HOW to assess value. But we will give you an insight on the factors to understand and consider, before you begin to assess the value of the gems.

What gives gems a value? What makes gems valuable?

Gems are valuable because of the following factors:

  • Beauty
  • Rarity
  • Durability
  • Demand
  • Tradition
  • Portability


To begin, beauty is the first attribute that we can see with our naked eyes. For most part, the 4Cs have been a big contributor for understanding the beauty of a gem. These are: Carat weight, Clarity, Colour and Cut. However, the 4Cs probably applies more to transparent, faceted gems. Other gem materials like jadeite-jade and nephrite-jade has its own unique grading system. Therefore, the beauty of a gem may also be described as the ‘quality’ of a gem.

Assessing value of gems
A set of blue sapphires put together for colour comparison. Colour is an important factor when assessing value of gems.


Rarity means uncommon, or unusual. Diamonds are rare because the yield of mining production is very low. For every 5carat total weight of diamonds mined, approximately 300 tons of ore needs to be processed. Similarly for rubies and sapphires, in many mining countries, the mining technique is still quite manual, although some are semi-automatic. Kashmir sapphires for example, are mined from very harsh conditions. Hence, explaining its rarity.

There are also some gemstones which are rare because of its phenomenal optical effects. In order to achieve perfect chatoyancy (cat’s-eye) or asterism (star), it depends on the rough material as well as the lapidary. When the best of the two comes together, the fashioned gemstone becomes very rare.

assessing value of afghanistan emeralds
Rough Afghanistan emeralds. These emeralds tend to be slightly lighter in colour and not as saturated as those of Columbian emeralds. However, beautiful green pieces are also very hard to come by. The value is in its ‘hard to come by’ factor.



Gemstones are valuable because of its durability. It doesn’t get damaged easily and therefore keeps its quality the same for a very very long time. Therefore, some pieces of gems and jewellery can be kept and passed down from one generation to another. Family heirlooms have very intrinsic value that is very hard to quantify. When assessing value of gemstones, we also will look at how well it has kept its durability, i.e. how well it has been maintain at its highest quality.

Durability involves a few factors: hardness, toughness and stability (to light, heat and chemicals). We will discuss these in the future blog posts.

Meanwhile, we do not want to see chips and scratches on our gems!

assessing value by duarbility
This amethyst has polishing marks on the surface. This is because it has a hardness of only 6.


Assessing value of gemstones to be continued…

We have discussed three reasons why gemstones are valuable. In fact, these factors applies also to diamonds and minerals, except for some variations in the details.

In the second part of this topic, we will continue to discuss on why gemstones are valuable.