Welcome to the awesome world of gemstones!
Whether you’re a jewellery enthusiast, a collector, a budding gemmologist or simply someone who appreciates the beauty of these precious stones, learning about the different types of gemstones is a fascinating journey.
From timeless diamonds to rare and exotic stones like alexandrite, each gemstone has its unique set of characteristics and properties that make it special and in this guide, we will:
- Look at the most popular and well-known types of gemstones, providing you with valuable insights into their origins, characteristics
- Answer some of the questions many people ask about gemstones
But before I get into the guide, let me introduce myself, my name is Paul Haywood FGA DGA and I’m a fully qualified gemmologist with the Gemmological Association of Great Britain (Gem-A) and my love and interest in gems was the reason why I decided to study and then teach about them.
So, with that out of the way, let’s begin our journey into the fascinating world of gemstones!
What Is A Gemstone?
Let’s start with one of the most fundamental questions about gemstones, which is “what is a gemstone?”
A broad definition is a mineral that is highly prized for beauty, durability, and rarity.
The problem with this definition is that not all gems are minerals because a mineral, according the the Collins Dictionary, is an inorganic substance occurring naturally in the earth but when it comes to gemstones, we have organic gems such as Pearls which are made by molluscs and Amber which is fossilised tree sap.
But let’s take a closer at the three highly prized characteristics in the above definition:
Beauty is in the eye of the beholder but colour, transparency, lustre and optical effects are all part of a stones beauty.
A gems durability is a combination of its hardness, toughness and stability, which are all important for both how the gem is cut and best used.
Rarity is relative but gemstones are rarer than other types of mineral or metals, for example Diamond is a lot rarer than Iron.
Precious vs Semi-Precious Stones
As we are talking about gemstone types, let’s have a look at one of the most commonly used ways of describing gemstones, which is Precious vs Semi-Precious:
- Precious Gemstones – this is Diamond, Emerald, Ruby and Sapphire (often called the Big 4)
- Semi-Precious Gemstones – everything else
The problem with this is that it is an antiquated and to be honest, completely stupid way of describing gemstones that we shouldn’t be using because there is now way to define the two!
People have tried to justify this by using factors such as rarity or value but both can easily discredited, for example:
- There are many gemstones including colour-change Alexandrite, Black Opal and Paraiba Tourmaline that are all rarer than the ‘Big 4’
- Prices for the ‘Big 4’ can range from less than $50 a carat to 6 or 7 figures per carat but many of the rarer gemstones will often range from hundreds to thousands a carat
And I don’t know about you but a rare gemstone worth thousands of dollars a carat doesn’t exactly sound like semi-precious to me. I’ve delved deeper into this is my Precious vs Semi-Precious Stones post.
If we don’t use precious vs semi-precious to differentiate between gemstones, then what do we use?
Well, there are a couple of broad categorisations such as Organic and In-organic materials or Diamonds and Coloured Gemstones.
But the best way that we categorise gemstones is based on their chemical composition and crystal structure and these are commonly known as Gem Families and there are two main types of these:
- Single Stones – these are gemstones that have a unique chemical composition & structure that is different to that of other gemstones and includes Diamond, Peridot and Iolite
- Varieties – this is where a group of gems share the same or a very similar chemical composition and structure but have recognised varieties based on different colours or effects
With nearly all of the gemstone families that have varieties, in their purest form the stones are colourless and the colours in the different varieties are caused by colouring elements such as Chromium and Iron but there are always exceptions to the rule, with the most notable being Garnet.
And there are some very important gemstone families that have varieties, with the most notable ones being:
The Beryl family of gemstones includes some of the most desirable varieties of gemstones, including:
- Morganite (Pink)
- Goshenite (Colourless)
- Heliodor (Yellow)
- Bixbite (Red)
The Corundum family is home to two of the most important and historically significant gemstones, which are:
The Garnet family of gems differs from the others as while Garnets have the same structure they have different chemical compositions, which is what causes the different varieties, including:
- Almandine & Pyrope (Reddish-brown)
- Spessartine (Orange)
- Tsavorite (Green)
- Demantoid (Green)
- Rhodolite (Purplish-red)
The Quartz family has two distinct types of gemstone in its family, which are:
Between these two type of Quartz, there are a number of desirable and important varieties, including:
Crystalline Quartz Varieties
- Citrine (Yellow)
- Rose Quartz (Pink)
- Prasiolite (Green)
- Rock Crystal (Colourless)
Polycrystalline Quartz Varieties
- Tiger’s Eye
Other gemstones families include Feldspar, which includes Moonstone, Labradorite and Sunstone and Zoisite, of which Tanzanite is the most well know variety.
Different Types of Gemstones
Now we have learned a bit about gemstones, lets take a look at some of the different gemstone types that are out there but I’m not going to list all the gemstones that are available as:
- Many are extremely rare and only really collectors stones
- Many aren’t suitable for use in jewellery for various reasons
So for this list of gemstones, I’ve included the most popular gemstones from a commercial perspective as these are the ones that you are most likely to come across when looking at or buying gems, whether loose or used in jewellery.
For each gem, I’ll also include the:
- Family it is part of
- Durability of the gem, broken down into hardness, toughness and stability
- The Refractive Index (RI)
- The Specific Gravity (SG)
Amethyst is the purple variety of the quartz family and its distinctive purple colour can range from a pale lilac to a deep, rich violet, which makes it one of the most popular quartz varieties and is often used in jewellery due to being a relatively durable gemstone.
- Birthstone: February
- Anniversary: 17th
|Quartz||7||Fair||Good||1.54 – 1.56||2.65|
Aquamarine is a blue-green variety of the beryl family whose colour can range from greenish-blues to the more desirable stones have a darker blue colour. Aquamarines are a popular choice for jewellery due to being a relatively durable gemstone and most gem-quality Aquamarines have very good clarity.
- Birthstone: March
- Anniversary: 19th
|Beryl||7 1/2||Good||Good||1.56 – 1.60||2.65 – 2.80|
Citrine is the the yellow variety of the quartz family and colours can range from pale yellow (sometimes called lemon quartz) to rich deep reddish-brown, with most desirable colours ranging from yellow to orangey-amber. A close relation to Amethyst, Citrine is a relatively durable gemstone that is often used in jewellery.
- Birthstone: November
- Anniversary: 13th
|Quartz||7||Fair||Good||1.54 – 1.56||2.65|
Cubic Zirconia (CZ)
Cubic Zirconia, commonly know as CZ is a man-made gemstone that is one of the best diamond simulants on the market and has been a popular option for cheaper jewellery since the 1970’s, while often dismissed as a cheap diamond knock-off, CZ’s are durable gemstones that are suitable for all types of jewellery.
|CZ||8 1/4||Good||Good||2.17||5.6 – 6|
Demantoid Garnets are some of the rarest and more desirable varieties of the garnet family, this green variety of garnet is only found in a couple of places in the world, with the Ural mountains in Russia being the largest source.
Due to being quite soft and also brittle, they aren’t ideal for use in jewellery and are only really suited to earrings and pendants.
|Garnet||6 1/2||Poor||Good||1.89||3.82 – 3.85|
Diamond is the most well known gemstone in the world and is categorised separately to all other stones. While colourless or ‘white’ diamonds are the most well known, diamonds can be found in many different colours, including blue, pink, yellow, purple and red.
As the hardest known natural material and a very durable stone, diamonds are understandably a very popular choice for all types of jewellery, especially engagement rings.
- Birthstone: April
- Anniversary: 10th & 60th
If you would like to learn more about Diamonds, then check out my Introduction to Diamonds post.
Emeralds are the most well known green variety of the beryl family and also one the most desirable member of the family, prized for it’s stunning green colour which can range from a light, pale green to a rich vibrant green, which is often found in high quality stones.
While a popular choice for jewellery, Emeralds are brittle stones and are better suited to pendants and earrings than rings.
- Birthstone: May
- Anniversary: 20th & 35th
Want to learn more about Emeralds? Then check out my Emerald Buying Guide, which covers these stones in much more detail.
|Beryl||7 1/2||Poor||Poor||1.57 – 1.60||2.65 – 2.80|
Garnet (Pyrope & Almandine)
Pyrope and Almandine Garnets are two of the most common varieties and share a similar appearance and physical properties with colours for these stones ranging from purplish-red (often called rhodolite garnet) to brownish-red. These garnets reasonably durable and are commonly used in jewellery.
- Birthstone: January
- Anniversary: 2nd
|Garnet||7 1/4 – 7 1/2||Good||Good||1.74 – 1.81||3.7 – 4.2|
Jade is one of the toughest gemstone materials and one of the few where jewellery is made from the gemstone, such as solid jade bangles. Jade is mainly known for its green colour, with Imperial Jade being the most desirable, jade can also be found in a range of colours including yellow and white.
- Anniversary: 12th
|Jade||6 1/2 – 7||Excellent||Good||1.66||3.3|
Opal is one of the world’s most beautiful and unique gemstones and due to their formation, you won’t find a pair of opals that possess the same play of colour.
There are different types of opal including the rare and desirable black opal, crystal and white opal all of which are usually cut into cabochons but due to their relatively poor durability are best suited to earrings or pendants rather than rings.
- Birthstone: October
- Anniversary: 14th
|Opal||6||Poor||Poor||1.40 – 1.46||2 – 2.2|
Peridot is one of the few gemstones that is only found in one colour and that is green and this green can range from pale yellowish green to a bright, vibrant green, which is the most desirable colour.
A popular choice for jewellery and often used instead of emeralds but they aren’t the most durable of gems and are better suited to earrings and pendants than rings.
- Birthstone: August
- Anniversary: 16th
|Peridot||6 1/2||Fair||Fair||1.65 – 1.69||3.32 – 3.37|
Ruby is the red variety of the corundum family and is one of the most highly prized and desirable gemstones in the world, it is also holds the title of the most expensive coloured gemstone. Rubies can range from pale pinkish-reds to deep, rich reds found in the finest stones.
Rubies are also a very durable gemstone and are a popular option for all different types of jewellery, including engagement rings.
- Birthstone: July
- Anniversary: 15th & 40th
Want to learn more about Rubies? Then check out my Ruby Buying Guide that covers these gorgeous gems in more detail.
|Corundum||9||Good||Very Good||1.76 – 1.78||3.8 – 4|
Sapphires are the other variety of the corundum family and while mainly known for being blue, sapphires are actually found in a range of different colours including, yellow, green, purple and orange. There are also extremely rare colours such as Padparadscha, which is named after to orangey-pink colour found in the lotus flower.
These range of colours combined with sapphires being a very durable gemstone makes them a popular option for all different types of jewellery.
- Birthstone: September
- Anniversary: 45th & 70th
Want to learn more about Sapphires? Then check out my Sapphire Buying Guide that covers these gorgeous gems in more detail.
|Corundum||9||Very Good||Very Good||1.76 – 1.78||3.8 – 4|
Tanzanite is one of the newest gemstones, having only been discovered in 1967 but has gone on to become one of the most popular gemstones due to the stunning colours, which can range from pale blue to rich, vibrant violet-blues and sapphire type blues.
Tanzanite has become a popular option for jewellery but it is quite a soft and brittle stone, meaning it isn’t the best option for rings.
- Birthstone: December
- Anniversary: 24th
|Zoisite||6 1/2||Poor||Good||1.69 – 1.70||3.15 – 3.38|
Topaz is mainly known as a relatively inexpensive blue gemstone, with colours ranging from pale to deep blue with trade names to match many of the varying shades. But Topaz can be found in many colours, including pink and yellow with the pinkish-orange ‘Imperial Topaz’ being both rare and desirable.
A popular option for us in jewellery due to being quite hard but aren’t the toughest gemstone due to having perfect cleavage, meaning they can be broken quite easily.
- Birthstone: November
- Anniversary: 4th
|Topaz||8||Fair||Good||1.61 – 1.64||3.5 – 3.6|
Tourmaline is a very unique gemstone as they can be found in pretty much any colour you can think of due to their chemical composition, with varieties including Rubellite (hot pink to red), Indicolite (blue) and Paraiba (neon blue), of which Paraiba is the most desirable and valuable. Tourmalines can often be found as bi or tri-colour stones, meaning a single stone posses two or three different colours.
Tourmalines are pretty durable gemstones, which makes them a popular option for use in jewellery but some varieties are more brittle than others.
- Birthstone: October
- Anniversary: 8th
|Tourmaline||7 – 7 1/2||Good||Very Good||1.62 – 1.65||3 – 3.1|
Natural vs Synthetic Gemstones
There is no way I could do a gem guide and not cover this topic!
What is the difference between a natural gemstone and a synthetic one?
Natural gemstones were created by nature whether by geological processes or organically grown. In the case of in-organic gemstones, this process from formation to being mined can take thousands or millions of years depending on the crystal.
Synthetic Gemstones – also know as lab-grown, lab-created etc are man-made versions of natural gemstones and share the same (or at least very similar), physical, chemical and optical properties as their natural counterparts.
There are many different methods of manufacture for synthetic gems, which include:
- Flame fusion – this is the most popular method for growing synthetic Rubies, Sapphires and Spinels
- Hydrothermal synthesis – this is a popular method for creating synthetic Quartz and Emeralds
- Flux growth – is used to create synthetic Rubies and Emeralds that look closer to the natural stones that ones grown by other methods
- Crystal pulling – a more expensive way of growing synthetic stones but can produce synthetic Alexandrite and high quality Corundum
In terms of value, synthetic gemstones are significantly cheaper than the equivalent quality natural stones.
There is also a third type of gemstones, which are simulants and many people often confuse these with synthetics but simulants are stones that have a similar appearance to a more expensive stone (and sometimes may even be sold as the more expensive stone) but have completely different physical, chemical and optical properties.
The best example of a simulant is Cubic Zirconia (CZ), which is a common Diamond simulant but is a completely different gemstone.
While gemstones are beautiful, they do need to be treated with care when being used in jewellery and understanding the differences in durability between stones can make your life easier and also your customers lives easier.
But because of the variety of gemstones that are out there, it takes a bit of learning to know the difference between these gemstones but also using them at the bench will give you some first hand knowledge of what they are like to use and you will break stones when setting but this is all valuable experience for the next time you try to set another one.