Welcome to the start of the Gemstone Diaries.

Before we delve into the fascinating world of gem collecting & trading we need to clarify some of the more common industry terms and areas of confusion;

What classifies a mineral as a Gemstone?

Well it needs to meet 3 conditions;

1. it must be Rare.
2. it must be Durable.
3. it must be Beautiful.

Of the three conditions durability is the least understood. Durability can be divided into two aspects, comprising (1) hardness and (2) toughness.

Hardness means it has a resistance to scratching and abrasion. Toughness means it is not easily chipped or broken. So a gemstone can be hard but not tough, like Diamonds, or tough but not hard, like Jade.

Hardness is the main criteria for gemstones and as such it is determined by a universally adopted scale, known as the Mohs Scale, with measurements based on Diamonds at the top, for hardness and Talc at the bottom, for the softest.

Just to clear up a myth regarding Diamonds; Yes they are the hardest mineral known to man but they are NOT the toughest. A Diamond cannot be scratched, except by another diamond (or equivalent) but it will chip and break if you knock it or take a hammer to it. In the past many rough diamonds were lost by artesian miners thinking that if they hit it with a hammer and it did not break it must be a Diamond. Many beautiful rough Diamonds were destroyed.

Precious vs Semi-Precious

The terms “precious” and “semi-precious” first came about in the mid-19th century in the West, which explains why Jade, despite being enormously important and valuable in China, was never considered a precious stone. Before this distinction, practically all gems were considered precious.

The term “semi-precious” was created mainly because of Amethyst. The stone was once adored by royals, until large deposits were found in South America and its commercial value dropped. A new term was then required to describe its downgraded status.

As an industry term, I feel it adds nothing more than confusion and is not generally used by gem traders. It’s a bit like saying someone is semi-pregnant or semi-dead. How can it be ‘semi-precious’?  It either is or isn’t!  The term is mistakenly used to determine ‘value’ and by default emphasises that Diamonds, Rubies, Sapphires and Emeralds are more valuable than other gemstones. This is a not the best way to assess gemstones. Here’s an example as to why; a treated, eye clean, 5 ct Ruby may be picked up in the market for say U$30-U$40 a carat, whereas an untreated, eye clean, 5 ct Red Burmese Spinel would command anything between U$3,000 to U$5,000 a carat.  Under these obscure terms, the Ruby is classified as ‘Precious’ and the Spinel as ‘Semi-Precious’! Note that many Crown Jewels have red Spinels in them instead of Rubies, click here for more on this.

Carat vs Karat

Gemstones are sold by weight. The standard weight is determined by Carat, with a ‘C”’ and abbreviated to ‘ct(s)’, which entered the English language in the 15th century as a measure of weight.

Many believe that the derivation of the term is from the italian ‘carato’ which in turn came from the Arabic, who borrowed it from the Ancient Greek word ‘κεράτιον’, meaning ‘carob seed’, which was used to measure weight.

One Carat is equivalent to 0.2 grammes, so 5 Carats is  the weight of 1 gramme. Gemstones are priced per carat. So a 2 carat stone will be quoted at U$x per carat and to get the total price multiply the carat price by the size of the stone; i.e. 2 x U$x per carat. Gemstone prices are exponential, the greater the weight the greater the value multiplier. A 1 carat stone may be valued at ‘U$500 a carat’ but a 3 carat stone may be valued at ‘U$1,000 a carat’ because larger stones are rarer.

‘Carat’ should not be confused with the word ‘Karat’, which is pronounced the same but used to determine the purity of Gold i.e 24 Karat/ 24Kt gold is the equivalent of 100% pure Gold.

Eye Clean

All gemstones are inspected through a jeweller’s loupe, aka a hand held microscope. Which is used to identify any inclusions in the gemstone, the cut & alignment of facets and  the general quality of the stone. A loupe magnifies the gemstone by 10. So  by looking through a loupe you are seeing everything magnified x10. However, when you look at a gemstone that has been set in jewellery i.e. a ring, you are looking at it normally, usually at arms length. If you cannot see any inclusions in it, it is classified as ‘eye clean’, i.e. it looks clean to the eye.

In my view and especially with coloured gemstones, ‘eye clean’ is one of the most important aspects to look for.  Having said that, there are always exceptions and some gems have little crystals in them, termed ‘ sugar’, which actually enhances the gem, giving it a treacle like lustre. Inclusions should not be seen as being bad, remember nature does not always create perfection.

The most important consideration is, does it look good to you? The human eye will naturally gravitate to quality gemstones.

Treatments

This is probably the area of greatest confusion. What is Treatment and how does it affect value.

Treatment in the gemstone world is where the gemstone has been enhanced in some way. The term enhancement is defined as any treatment or process, other than cutting and polishing, that improves the appearance, durability, value or availability of a gemstone. In today’s gem marketplace, many gemstones have been enhanced by a variety of methods. Such processes may range from simple heating (such as with tanzanite or sapphires) to high-tech irradiation (such as blue topaz).

However , treatments of gemstone has been undertaken for hundreds of years, from basic heating to further enhance colour to modern day fissure filling in rubies, and is nothing to shy away from. Without treatment we would not have certain gemstones or those gemstones would be so rare and expensive that we would never have the opportunity to own one.

The most important thing to remember is that Treatments always need to be disclosed. If you are going to buy a ruby that has been treated you need to be informed. Once informed you can then compare it on price, cut, clarity and size to a gemstone that has not been treated, if they exist for that type of gemstone. Note that there are gemstones that are more likely to be treated than others. I’ll cover that later.

Lab Testing Certificates

My rule is: Don’t buy the Certificate, Buy the Stone!

Too many people get hung up on getting a Lab Tested Certificate and pay less attention to the actual stone. If you like the stone, you’ve been given full disclosure on any treatments and it’s the right price for you, then buy it. You aren’t going to wear the Certificate. The cost of obtaining a Lab Test Certificate would be disproportionate, unless it’s a very high value stone or traditionally it’s a quality Diamond, where the cost is justifiable. The Diamond industry seems to be hung up on Lab Test Certificates. I think it’s because its the default stone of choice for engagement rings, stone prices are based on a mad formula of three months wages and those buying, understandably, don’t have any experience in what they are getting for their money. The Lab Test Cert then becomes an insurance policy.

I will cover Lab Certificates in due course, as there are universally accepted Labs and some that issue Certs that are not worth the paper they are written on.

I hope this has given you a good understanding of some of the basic terms and my take on them.

I am looking forward to the next installment of the Gemstones Diaries where I will look to cover the big 4: Diamonds, Rubies, Sapphires and Emeralds. If you want to feast your eyes on some of my gemstone collection have a look here.