What Do I Look For When Shopping for Diamonds or Buying Coloured Gemstones?


(Part 4 of a series of 5.)

“Shopping for Diamonds is Harder Than I Expected!”

Let’s say you’ve decided to propose and buy the ring (whether you shop with your fiancee to be or not). You’ve figured out what she likes, you know your jewellery metals, and you’re now shopping for an engagement ring.

But suddenly you’re faced with the realisation that that shopping for diamonds and gemstones requires a lot more knowledge than you had originally expected.

Why do we need to know so much about buying coloured gemstones and diamonds?

Diamonds: A Complicated Commodity

Why do diamonds have so many details which determine their value? Well, it’s the market’s fault.

For as long as any historian can remember, gemstones have been a very useful trading commodity. Their rarity and beauty gave them desirability, whereas their small size meant they were a very portable or even wearable form of wealth.

This also meant there has always been a ripe market for fakery. There isn’t a precious stone you can buy out there that doesn’t have a fake or falsified form. When people study gemmology, most of what they are actually studying is how to spot a fake.

When it comes to fakery, however, Diamonds are in a class by themselves. Because of their status as a controlled commodity, attempts to fraudulently make them abound.

To protect both retailers and customers from fraud, all diamonds above a certain size (0.4ct) are certificated. This means they come with a certificate detailing all of that diamond’s information. To help identify that diamond’s unique properties, the certificate goes into great detail as to the diamond’s properties. Since no two diamonds have identical properties or dimensions, this certificate confirms the diamond’s value and origin.

Also, to protect customers like you from having to deal with conflict diamonds, there is a strongly enforced provenance system called the Kimberley Process. This process provides tracking all the way back to the mine for the origin of a stone. This information is included on your diamond certificate.

The GIA came up with a grading system back in the 1950’s to allow for the specific identification of diamonds. They were called the Four C’s.

The Essentials You Should Know About Diamond Quality (the Four C’s)

For diamonds and other gemstones, the Four C’s are the main way we judge the quality of diamonds and their value.

  1. Clarity
  2. Colour
  3. Carat
  4. Cut

The 4C’s do have an effect on the value of coloured stones, but we don’t give them standard ratings the way we do diamonds.


This is a measure of how many imperfections (or Inclusions) can be found inside a diamond. The clearer the diamond, the better looking the reflections.

Also, as these inclusions are never the same between two stones, these inclusions are used to keep track of the diamond and ensure it is both a real diamond as well as conflict free and sustainably sourced.


Not everyone is aware but diamonds come in a rainbow of colours, from white to pale blue to darkest red, most of the time people tend to most value either pure white or strong fancy colours. The barely tinted stones in between are considered less valuable.

A colour rating of D is considered effectively colourless.


The word Carat has meaning both in terms of the gemstone size, and the quality of gold. For gemstones, it’s a measure of weight. 100 points equals one carat. For example, a 0.4 carat diamond would also be called a 40 point diamond. Diamond’s over 0.4 carats are required by the Kimberley Process to have certification to prove they are conflict free and not stolen.


This term refers both to the quality of the faceting as well as the chosen shape of stone.

There are several different types of cuts we frequently use.

Alternative Cuts

The cuts listed above are by no means an exhaustive list of the possible shapes for a gemstone. They’re merely the most common and popular.

Another type of gemstone shape we see with coloured stones is the Cabochon. The Cabochon is an unfaceted stone with a domed top and flat bottom. When a gemstone is too soft to facet, we will often see it available in cabochon form.

Are there Any Alternatives to Diamonds?

As a design feature, I like to use in jewellery because of the stone’s toughness and the incredible colours it produces thanks to a thing called perfect refraction. But your fiancée to be may like things a little bit different. So for those who’d like to add a bit of colour to their ring, we have options…

On the right we have 6 of the most common alternatives for diamonds, in their most common colours. All of these can easily be used to substitute for a diamond as a main stone.

If you’re looking for a little colour on the side stones, rubies and sapphires can also be used in pave setting.

Note that while these are the most popular choices for rings, these aren’t by any means the only colours or gemstones available. If you know your partner likes their birthstone, we can use those as well. Just ask and we can provide additional options.

A popular design choice is to surround one of these coloured stones with diamonds to make a cluster setting as seen on the Princess Diana ring.

Things To Look For When Buying Coloured Gemstones

When buying coloured gemstones, there are a couple of things which are worth bearing in mind.

First, since we don’t have the same kinds of rigorous grading on coloured gemstones that we do on diamonds, their ratings for quality work a bit differently. The easiest way for you to tell if a gem is good or not is simply to look at both the price and quality. If it looks too good to be true on the price, it probably is.

Second, it is illegal for a company to misrepresent the quality of what they’re selling. If a coloured gemstone has been artificially treated to make it look better, or it has been artificially grown, they are legally obliged to tell you, as both of these will affect the price.


There is a bit of information you need to keep in mind about shopping for diamonds and coloured gemstones, but there are ways to make learning this manageable. Remembering mnemonic helpers like the 4 C’s or even carrying a crib sheet can make it easier for you to remember these key details for when you need them in the jewellery store.

Ultimately, bear in mind that any jeweller worth doing business with should want you as the customer to get the best value for your money. So go with your gut– if a jeweller doesn’t seem honest, you don’t have to do business with them.

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