How to Buy Colored Gems and Which Questions to Ask


How to Buy Colored Gems and Which Questions to Ask 

"What do you mean 95% of all rubies and blue sapphires in the world have been treated?!"

An exclamation I often hear when discussing gemstones. I also had no idea about this before I dove into gemology. While it's nice to assume that all gemstones are a product of nature, completely untouched by humans, it's just not the case, and it would even be impossible. Why? Because there simply aren't enough natural and untreated gemstones to meet the demand in the market.

Without treatments, there would virtually be no gemstone jewelry industry! As the most commonly known stones have virtually all been treated, such as amethyst, citrine, blue topaz, aquamarine, emerald, ruby and blue sapphire. 

Gemology, Gemologist, Know your Stones

In fact, almost all rubies and blue sapphires have been heat-treated to enhance their colour or to improve the clarity and make the stone look more attractive. 
There's nothing wrong with that - it is a fully acceptable treatment for gem laboratories, gemologists and gem dealers around the world. 

Most (potential) buyers of gemstone jewelry on the other hand, have no clue about these gemstone treatments. And only want "natural gemstones". Until they hear the price of natural stones. Or feel scammed by the idea that a stone has been treated. 

Although there are definitely unacceptable or questionable gem-treatments out there, a lot of treatments are totally OK. Don't let a lack of information make you miss out on these exquisite colored stones of nature! When armed with a bit of research and prepared with some questions to ask your jeweler or gem dealer - you can enjoy a wonderful gemstone that suits your budget and avoid any pitfalls or embarrassment that could follow after your purchase.

Here are a few things that are good to know before buying colored gemstones:

1. Treated gemstones are not "fake" and are different from "synthetic" gemstones

Buying Coloured GemstonesSo, what does all of this mean?

First, a few definitions to further explain the difference between real vs. fake crystals and gemstones...

natural gem is any gemstone which is entirely the product of nature. It is unaltered by humans in any way, except for ordinary cutting and polishing.

treated gem is any gemstone that has been altered by humans, beyond ordinary cutting and polishing. For instance, a heat-treated ruby or an oiled emerald.

A synthetic gem is the same as a natural gem (in terms of physical, chemical and optical properties), EXCEPT that is has been made by humans. So, this stone has been made in a lab somewhere. For instance, there are synthetic versions of diamonds, rubies and blue sapphires. 

Then there is what we call a simulated or imitation gem and, like the synthetic gems, these have been made in a lab. There's a big difference though between synthetic and simulated gems. Simulated gems don't have a natural counterpart like synthetic gems have. 

Simulated gems have been created solely to replicate the physical, external appearance of a gem. But their physical makeup is totally different from the stone they're trying to imitate. For instance, common diamond simulants are cubic zirconia, GGG (Gadolinium Gallium Garnet), moissanite and others.

Or in colour stones: red glass or a red tourmaline which is used to imitate a ruby can also be called imitations or simulations. So they imitate the external look of a diamond or colour stone but do NOT have the same composition as a natural diamond / colored gem in terms of optical, physical and chemical elements. 

You could call the stones from the two last groups - the synthetics and simulants - "fakes". I'm not judging though.

Buying Tip: It's perfectly alright to buy them as long as you're aware they were made in a lab and you pay less than their natural counterpart or the stone they're trying to imitate. 

So, summing up, a natural, treated stone is NOT a fake stone at all as people sometimes seem to think! It's still a natural stone that has had some treatment after it was mined from the earth. And many of these treatments are alright and acceptable in the market. So don't immediately walk away when you hear the word "treatment".


2. There are many types of treatments specific to the type of gemstone

Different types of stones have different treatments because each stone species is different (chemically speaking) and responds in different ways to different treatments. 

For instance, an emerald is a very brittle stone and would never survive the high temperatures required for a heat-treatment which is a normal treatment for rubies and sapphires though. So, another treatment is used to beautify emeralds; oiling. Oiling fills internal fractures and improves the clarity and/or colour. This treatment is, however, not durable.

A ruby or sapphire, on the other hand, can handle these high temperatures of heat-treatment resulting in a durable, more beautiful red or blue stone. Heat-treatment is used to enhance colour, clarity and, in some cases, both together. Heat-treated rubies and sapphires are considered acceptable in the gem trade, provided they are properly disclosed as such at the point of sale.

In fact, heat-treatment can be traced back to as early as the Egyptians. Although it wasn't until the 1970s that it became common practice in Thailand where the process was industrialized and fine-tuned. This was done for one valid reason only: to make naturally rare rubies and blue sapphires more available to more consumers for a more attractive price. And, don't get me wrong, even with heat-treatment, a fine-quality ruby or blue sapphire can still be very expensive!

3. Treated stones are less expensive than untreated stones

Gemstone Ring, Cobalt Blue Blaze
Tanzanite Gemstone Ring by Eva Gems & Jewels

In general, treated gemstones are and should be less expensive than their similar, untreated counterparts. 

Makes sense, right? When you compare two similar blue sapphires: both 5 carats, both equally good blue colour, both equally clean on the inside of the stone (with few inclusions) and both equally well cut... Then the one which has had a heat-treatment in order to achieve such qualities will be less expensive than the other stone which came out of the earth already in this beautiful state.

It's just very rare to find an intense blue sapphire like this in nature, so the price of this untreated stone will be higher and connoisseurs are willing to pay for it. In fact, there can be a waiting list for a stone like that...

To give you some idea of price, if you're looking for a good quality, 5+ carat blue sapphire from Kashmir or Ceylon (Sri Lanka) and your budget is between $2,000 - $10,000, you may need to opt for a treated stone. Yep, a good quality, untreated blue sapphire of this origin (considered the most beautiful in the world) and size will easily surpass $10,000. 

4. Natural, untreated gemstones are not always the 'best'

Hopefully you have by now realised that treatments are not, by definition, a bad thing at all. An acceptable treatment can bring a good quality gem, which might otherwise be completely out of your reach, within your reach. 

Given the limited choice we have, and depending on your budget and personal preference, I'd actually prefer a larger, treated gemstone over a smaller, untreated gemstone of similar quality. At the end of the day, we're talking about visual, sparkling beauty. 

And sometimes bigger is just better. 😉

The tricky thing is that consumers generally have no idea about treatments so how would they know what to ask their jeweler? Let alone which questions to ask? And jewelers, for this reason may try to avoid the word 'treatment' when selling to consumers. They fear the buyer won't like that word when they bring it up... and they're probably right.

In addition, sometimes a jeweler simply doesn't know whether the stones in his jewelry have been treated because the vast majority of jewellers are not gemologists. The reality is that jewelers are at the end of the market chain which can have many dealers and manufacturers involved after the mining process, whereby anyone could have carried out the treatment. 

Precious stone dealers usually do know whether their loose gemstones have been treated or not because they're closer in the chain to the cutters/treaters and wholesales and so have more information about what's been done to the stones. They may even have carried out the treatment themselves. 

In any case, whether you're buying gemstone jewelry from a jeweler or a loose gemstone from a gem dealer, you should prepare yourself ahead of time by knowing which questions to ask...

5. What to ask your Jeweler or Gem Dealer


Finally, how can you protect yourself when purchasing gemstones or gemstone jewelry?

Ask these questions and "interview" multiple jewelers or gem dealers for similar gemstones...

Let's assume for the example that you're looking at a loose, unmounted stone or a centre stone in a ring of which you'd like to know more.

First ask:

1. Is this stone natural or synthetic?

If they answer that the stone is natural: great! Move on to the next question. If they answer synthetic: leave the store... Unless you're totally OK with a gemstone that has been made by humans in a lab and which feels better to your wallet. 

Side-note: synthetic diamonds are the exception to this rule as they are actually not cheap at all because the process to make larger synthetic diamonds is time-consuming and costly. 

Next question (if they replied that the stone is natural):

2. Has this stone been treated?

Now, some jewelers may simply repeat that the stone is natural and look at you as if you're nuts because they think they just answered that question.

Remember, most jewelers are not gemologists and they may not know that you're now asking a totally different question. In that case, politely insist "Yes, I know it's a natural stone but I would like to know if the stone has been treated at all? Was it heated, for instance?"

Then they'll know you've done your research. They should be able to give you a better answer, ask a more senior staff member or refer you to someone who has studied gemology to help you out. They may also give you a certificate to review. If not, it might be best to search for a jeweler that can provide you with more information about the gem(s) you're interested in. 

Buying Tip: Once you know whether the stone is
(a) natural and treated or
(b) natural and untreated (thus more expensive),
know that today it is a safe practice to ask for a lab certificate on any ruby, sapphire or emerald purchase over $1,000

For other gems or stones of lesser value, they probably won't have a certificate available. There are exceptions, of course. There can be equally high value gemstones such as spinels, certain tourmalines or garnets that can also be sold with a certificate. 

When asking for a certificate, make sure the following points are covered:

  • it comes from an internationally reputable gem lab such as Gübelin, GRS, GIA, SSEF, AIGS and never from a small, local lab. 
  • it states the name of the stone and, regarding rubies and blue sapphires, whether it has been heat-treated or hasn't been treated. If you see other treatments besides heat, you should ask to see another stone or look elsewhere.
  • regarding even more expensive stones, the certificate can state the origin of the stone such as 'Burma/Myanmar' or 'Ceylon/Sri Lanka' which is even better if you want to sell the stone later on. These origins are desired by gem collectors and hence the stones will be even more attractive. 

The takeaway:

Heated stones, such as rubies and blue sapphires or aquamarines are not fake at all, they are natural stones that have undergone a normal and perfectly acceptable treatment.

It is partly your job to do some research and enter a store prepared with some questions, particular for such an exquisite product. Even better still, go to a store with a good reputation or directly to a gemologist who can guide you along the way so you can be sure you find the quality stone you want that suits your personal preference and your budget. 

To know how to buy colored gemstones and understand more about these special products, their craftsmanship, quality or background, means that you'll come to appreciate and enjoy them more. 

Finally, if you're not okay with any type of treatment and you have a bigger budget, then always go for a naturally beautiful, untreated precious gemstone in the biggest size you can afford. These stones will be more rare in nature, harder to find on the market and therefore, will have a higher price tag. 

But so worth it.

Good luck!


I hope this helps you on your gemstone journey and if you are looking to source a special colored gemstone or to create your own bespoke ring, start by booking a complementary consultation with Eva or continue to browse the website for more information on our bespoke jewelry process or explore our atelier collection

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