All about gemstones

What you need to know about gemstones in jewellery so you can make good decisions

When it comes to gemstones, not only are there a lot of different types and colours to choose from, there are also plenty of traps for the unwary and ill-informed.

For that reason, the best advice we can give you is to choose your supplier carefully!

Of course, we take great care to make sure the gemstones we supply to our customers are ethical in every possible sense. But if you do decide to go elsewhere, we hope this information will help you avoid the pitfalls of gemstone buying.

How do you know a good supplier when you see one?

It’s easy to get ripped off when it comes to gemstones.

Common deceptions include things like non-disclosure of imitation, synthetic and treated gemstones. It’s easy to be misled if you’re not dealing with a reputable trader.

Take particular care if you’re buying on-line, especially from overseas!

Take extreme care buying online

Be very wary of buying in marketplaces like online auction sites and pay special attention to the point of origin.

In Australia your purchases are protected by the Department of Fair Trade and you have recourse if something isn’t right.

And of course, when we supply your gemstones, you don’t have anything to worry about.

However, purchase off-shore and you may not have the same protections available to you.

Qualifications and industry certifications to look for

Keep an eye out for the following if you do decide to purchase off-shore or online:

Gemmological qualifications, usually indicated by letters such as

  • GG: Graduate Gemologist. Awarded by the Gemological Institute of America
  • FGA: Fellow of the Gemmological Association of Great Britain
  • AG (CIG): Accredited Gemmologist. Awarded by the Canadian Institute of Gemmology
  • FCGmA: Fellow of the Canadian Gemmological Association
  • FGG: Fellow of the German Gemmological Association

In Australia, look for the letters FGAA (Fellow of the Gemmological Association of Australia). And in case you were wondering, Melinda has FGAA certification.

Appraiser credentials such as:

  • AA-CJI: Accredited Appraiser of the Canadian Jewellers Institute. 
  • AM: Accredited Member of the American Society of Appraisers. 
  • ASA: Accredited Senior Appraiser of ASA ( the American Society of Appraisers). 
  • CAPP: Certified Appraiser of Personal Property. 
  • CGA: Certified Gemologist Appraiser. 
  • CMA: Certified Master Appraiser. 
  • CSM: Certified Senior Member of the (NAJA). 
  • MGA: Master Gemologist Appraiser. 
  • ISA: International Society of Appraisers Accredited Member. 

If you can’t find evidence of any of the above qualifications or certifications, we’d recommend finding another supplier.

Once you’ve done your homework and are happy with the supplier you’ve found, here are all the things to consider when choosing a gemstone. 

Thanks Melinda and Chris for the phenomenal job you did with our rings. To take our very abstract ideas and to turn them into something real was an incredible experience. We came to you because we wanted something ethical, but we ended up enjoying the process because you guys were so keen to help us and that we have could create one of a kind rings – the ethical part became an afterthought. Thank you!

Jemima from Sydney

The four gemstone Cs, plus H

When choosing a gemstone, you need to assess cut, carats, clarity and colour. As it is with diamonds, the value of a gemstone depends on its rarity, size and quality.

Unlike diamonds though, you also need to consider hardness.

Choose a gem that’s ‘tough’ enough

When you’re choosing a gemstone for an engagement ring, it’s also important to also consider ‘H’ — hardness. Many gemstones are ‘soft’ or fragile and can easily get damaged when worn on the hands.

Large custom cut morganite claw set in a recycled platinum ring with matching fitted wedding ring

Large morganite set in recycled platinum. Note the wide claws designed to protect the edges of the stone.

You’ll see when we talk about gemstones here, we usually only mention types that we consider suitable for setting in rings. (Where they’re more likely to be exposed to rough handling.)

That said, where there’s a will, there’s usually a way.

Design to limit the risk

Emerald is a classic example of a popular gemstone that’s relatively fragile. yet you see them everywhere.

Take a close look and you’ll see they’re most often held in a bezel or ‘roll-over’ setting to protect the edges and corners.

1. Colour

When it comes to colour, the ‘right’ colour is really a matter of personal taste.

Generally, the more vivid and uniform the colour, the more valuable a stone will be. However, if you’re looking for subtlety, that rule goes out the window.

How is colour described?

In gemstones, colour comprises of:

  • Hue — its pure spectral colour (from red to violet)
  • Intensity — the brightness or dullness of the colour
  • Tone — the amount of background white, black, grey or brown
  • Distribution — the evenness (or unevenness) of colour

The colour of a gemstone is a combination of its pure spectral hue and background tint.

The pure spectral and background colours go together to create the tone.

For example, if white is present with red, the gemstone will appear lighter in colour. If black is present, the gemstone will appear darker.

Often, the closer a gemstone is to the pure hue, the more valuable it is.

Light source is important

By the way, the light source you use is very important when evaluating a gemstone since different types of artificial lights emit different spectra.

This can have a significant impact on the appearance of a gemstone’s colour.

Fluorescent lights are weak in red rays (they’re ‘cool’) — this can darken red gemstones and give them a purple tone.

Blue gemstones (like sapphires), are best viewed under fluorescent light or in daylight. Under incandescent light they appear much darker — almost black.

Be aware too that background colour impacts on how a gemstone appears.

Red gemstones appear even redder when viewed on an orange or yellow background.

White diamonds are often displayed on a blue background to reduce any yellow tones.

What you see may not be what you get

Perhaps one of the most common ways gemstone buyers are deceived is through the alteration of the colour of a gemstone. This can be achieved by chemical or radiation treatment.

Likewise colour can be altered by adding a coating or soaking the stone in coloured oil. It’s even possible to pass one gem variety off as a completely different gemstone altogether.

Be wary! Again, make sure you’re dealing with a reputable trader.

Heat treatment is usually okay – when disclosed
Image of a gorgeous vivid blue of Tanzanite set in a platinum ring with pave set diamonds in the band

The gorgeous vivid blue of Tanzanite can only be revealed as a result of heat treatment

By the way, heat is another way of improving colour. When properly disclosed however, it’s not generally frowned upon within the industry.

Tanzanite is a great example of a gemstone that would look very ordinary were it not heat-treated as a standard practice.

2. Clarity

As it is with diamonds, the clarity of a gemstone is affected by flaws and inclusions.

But, unlike diamonds, in some gemstones certain types of inclusions can actually be very desireable.

Expect to see flaws and inclusions

Flaws (or ‘feathers’) are generally more common in coloured gemstones than they are in diamonds.

As long as they aren’t in a vulnerable spot that will weaken the stone then it isn’t something most people worry about.

Image of a Tanzanian Fair Trade ruby showing a black inclusion

Fair-trade Tanzanian ruby showing an eye-visible black inclusion at about 3 o’clock

As for inclusions, their aesthetic importance varies with the tone of the gemstone. The darker the gemstone, the less visible inclusions are.

Inclusions are more visible in light, almost transparent gemstones.

Beware ‘flawless’ gemstones

Be warned! Flawless gemstones are rare and expensive. So if you do encounter a ‘flawless’ gemstone, view it with suspicion. It could be an imitation or a synthetic.

The only way to be certain is to have it tested by a professional gemmologist.

Inclusions can be desirable

Finally, the presence of inclusions can, in some instances, be desirable.

Gemmologists often use the type of inclusion to accurately identify a gemstone.

Certain inclusions will confirm a gemstone’s rarity (or not).

Two gemstones may look the same to the untrained eye, but one could be much more valuable than the other because of its origin.


3. Cut

As with diamonds, it’s the cut that reveals not just the value, but the true beauty of a gemstone.

Cut can bring a stone to life … or kill it

Cut quality affects the depth of colour and the liveliness of the gemstone.

Poor cutting can cause an otherwise beautiful gemstone to look drab and dull. On the flip side, good cutting can’t enhance a low-quality gemstone.

When the gemstone you’re looking at reads well but looks below par, examine the cut.

If the cut is good, you can assume the gemstone wasn’t good to start with.

If the cut is poor, you could (possibly) be looking at a good gemstone cut badly.

And now the good news

A good quality, but poorly cut gemstone can easily be recut, usually at relatively little expense.

However, do keep in mind that gem cutters are not magicians. They can only subtract, so the recut gemstone will be smaller than the original.

To see how a gemstone can be transformed, take a look at the evolution of this morganite ring.

4. Carat (weight)

Between different types of gemstones, carat weight is not an indicator of relative size.

In other words, carat weight is only useful as a size indicator when comparing the same type of gem.

Specific gravity varies by gem type

Different gem materials have different densities (specific gravity).

As a result, whilst you may have two gems of exactly the same physical dimensions but of different types – say, garnet and sapphire – they will have different carat weights.

This is why gemstones are most often described by their physical dimensions rather than by their weight.

Bigger does not always mean more valuable

Sure, when it comes to gems like emeralds, rubies, sapphires, alexandrite and the like, larger stones attract higher prices by weight.

But other gemstones – particularly those from the quartz family – are readily available in sizes over 10 carats and do not attract a premium just because they’re big.

5. Hardness

When talking about hardness in relation to gems, we’re referring to ‘scratch’ hardness. That is, how likely the gemstone is to get scratched or chipped during day-to-day wear.

The harder a stone is, the safer it is from this kind of damage.

Take appropriate precautions in your design

You can set some softer gemstones if you take appropriate precautions in the ring design. For example, using a bezel setting rather than a claw setting. It all comes down to personal preference and the risk you’re prepared to take.

Image of an emerald gemstone bezel set in a ring to protect the stone's edges

Emeralds are a relatively fragile gemstone and are usually bezel-set to protect the edges and corners of this type of stone

Mohs’ scale of hardness

Hardness in gemstones is measured on Mohs’ scale, which rates gemstones from 1 to 10.

Talc is softest. Diamond is hardest.

By the way, it’s important to know that the Mohs’ scale isn’t linear. The ‘gaps’ get bigger as the hardness increases, particularly between 9 and 10.

Diamond is exponentially harder than the next hardest (corundum, sapphire and ruby).

If you want to claw-set a gemstone for everyday use, we recommend that you do not choose a gemstone with a hardness of less than 8.0 on Mohs’ scale.

If you choose a bezel or channel setting, you can go down to 7.0 providing the gemstone is otherwise quite robust.

Synthetics are not “imitations”

Contrary to popular belief, a synthetic gem material is not an imitation. They’re the real deal, just not created in the same place as their natural counterparts.

What are sythetic gemstones?

Synthetic gemstones refer to laboratory grown gems that have the same physical, optical and chemical properties as their natural counterparts.

Synthetic gemstones that don’t have direct natural counterparts are called ‘imitation’ gemstones. If you’re aware of what you’re purchasing, there’s nothing wrong with purchasing synthetic material.

To learn more about synthetic gems and diamonds, visit our section on lab-grown gemstones.

Note: For those of you who prefer not to buy mined gemstones or diamonds, we can offer you a variety of synthetic alternatives.

Want to start designing the perfect ring?

If you’d like to start designing the perfect ring for your partner (or yourself), send us a quick email (preferred) or call us on 07 3379 2596 to have friendly chat about your options.

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