How to Buy Loose Gemstones – Find the Best Gemstones for Your Custom Jewelry

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

Gemology Gemstone Audrey Hepburn Whoa

A typical exclamation I hear from people looking to buy colored gemstones ????

I also had no idea about this before I dove into gemology and became a gem dealer. We somehow assume that ALL gemstones that end up in our jewelry were just mined from the earth, perhaps cut and polished and that's it. That the stones haven't been altered or touched any further by humans... I wish, but that's not the case and also, would be impossible.

Why? Because there simply aren't enough natural and untreated gemstones to satisfy the demand in the market. In other words, natural gemstones that are of great quality when they're mined from the earth WITHOUT any human alteration to the stones afterwards are incredibly scarce.
And come with a price tag.

Without treatments, there would virtually be no gemstone jewelry industry and you probably wouldn't be able to wear amethyst (purple), citrine (orange, yellow), blue topaz, aquamarine (light blue), emerald, ruby and blue sapphire jewelry pieces, to name a few commonly treated gemstones... 

And to answer the question, yep, almost all rubies and blue sapphires have been heat-treated to enhance their color red and blue or to improve the clarity of the stone, and make the stone look more attractive. Nothing wrong with that - it’s a fully acceptable treatment for gem laboratories, gemologists and precious stone dealers around the world.

Most (potential) buyers of gemstone jewelry on the other hand, have no clue about gemstone treatments. They’ll talk about wanting only a ‘natural gemstone’ without knowing what that means exactly. And, until they hear the price. Then treatments appear not so bad after all…

Or they'll feel scammed when they hear about treatments and will think twice before even considering to buy a colored gemstone. Instead opting for the ‘safe diamond’ because they’ll last forever, they're never treated and don’t have these issues, right?


Although there are definitely unacceptable or questionable gem-treatments out there, don’t let this fear or rather lack of information make you miss out on these exquisite 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!

Things that are good to know about how to buy loose gemstones:

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

So, what's the meaning of all this 'natural', 'synthetic', 'fake' and 'treated' and how do they differ?...

Let me give you some dry definitions at first ???? 

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

And a ‘treated gem’ is any gemstone that has been altered by humans, beyond ordinary cutting and polishing.

A ‘synthetic gem’ is the same as a natural gem (in terms of physical, chemical and optical properties), EXCEPT that it has been made by humans.

Buying Colored Gemstones

The candy store... checking out some gorgeous colored stones, some heated and some not.

So, this stone has been made in a lab somewhere. There exist, for instance, synthetic diamonds, rubies and blue sapphires.

These synthetic stones you can call the 'fakes'.

Am not judging, it's perfectly alright to buy them as long as you know they were made in a lab and they're cheap!

So, a natural, treated stone is NOT a fake stone which people sometimes seem to think. It's still a natural stone that has had some treatment after it was mined from the earth.

2. There are many types of treatments specific to the gemstone - not all treatments can be applied to all gemstones

There are many types of treatments that I won’t go into now but some important ones are: heat-treated rubies and sapphires, oiled emeralds and stabilized turquoise.

Different types of stones have different treatments because each stone species is different (chemically speaking) and so, 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. It would probably crack. So, another treatment is used to beautify emeralds: oiling. Oiling fills internal fractures and improves the clarity and/or color. 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 actually used to enhance color, clarity and in some case both together. 

So, heat-treated rubies and sapphires are considered acceptable in the gem trade provided they are properly disclosed as such at the point of sales. In fact, heat-treatment can be traced back to as early as the Egyptians, however it wasn’t until the 1970s that it became common practice in Thailand. The Thai industrialized and fine-tuned the heating-process for rubies and blue sapphires.

They did this for one valid reason only: to make naturally rare rubies and blue sapphires available to more people for a more attractive price than would have been possible without treatments.

And don’t get me wrong, even with heat-treatment, fine quality rubies and blue sapphires can still be very expensive!

3. Treated stones are cheaper than untreated stones

Oversized Gemstone Ring Tanzanite

Not a blue Sapphire but a Tanzanite, a stunningly violet gemstone that's also typically heated.

Or rather, 'less expensive'...

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

Makes sense, right? When you compare 2 similar blue sapphires: both 5 carats (i.e. big…), both equally good blue color, both equally clean on the inside of the stone (so, with few inclusions) and both equally well cut, then the one which has had a heat-treatment in order to achieve this good color and clarity will be less expensive than the other stone which came out of the earth already in this amazing blue and with few inclusions.

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 some idea of price, if you're going after a good quality, 5+ carat blue sapphire from Kashmir or Ceylon (currently, Sri Lanka but often still called 'Ceylon' by dealers) - which are considered the most beautiful ones in the world - and your budget is between $2,000 - $10,000, you may need to go for a treated stone. A good quality, untreated blue sapphire of this origin and size can easily surpass $10,000.

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

As I hope you're starting to feel by now, treatments are not by definition a bad thing at all. On the contrary, especially a treatment like 'heating' is OK provided it's disclosed as such promptly.

A treatment like this will bring a stone like a good quality ruby or blue sapphire - which might otherwise be completely out of your reach - within your reach. Also a low grade stone that's been elevated to a very high grade due to this durable treatment becomes very interesting all of a sudden. This is the reason they can be reasonably priced after treatment compared to untreated stones which are already extremely highly priced.

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 though that as consumers generally have no idea about treatments, how would they know to ask their jeweler about them? Let alone what questions to ask?

And jewelers (selling to consumers) for this reason may try to avoid the word 'treatment'. They'll probably fear you won't like that word when they bring it up. And they're probably right... 

OR a jeweler simply doesn't know whether the stones in his jewelry have been treated because the vast majority of jewelers 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.

So, a jeweler may simply not have that kind of information, he didn’t ask his supplier or the supplier assumes the jeweler knows about the very common treatments of certain stones…

Precious stone dealers usually do know whether their loose stones have been treated or not because they're closer in the chain to the cutters / treaters and wholesalers 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 loose gemstones from a gem dealer, you'd better come prepared yourself with some questions which I'll show you below!

5. Thai masters of heat-treated rubies and blue sapphires

This specialization in and focus on heat-treatment of rubies and blue sapphires by the Thai in the 1970s made Bangkok very wealthy and has turned it into the number 1 gem-trading hub in the world with many reputable gemstone dealers

Initially only for rubies and blue sapphires but later for all colored gemstones (except for emeralds, which main trading center remains Colombia, the mining place of the most beautiful emeralds in the world, and for which Jaipur remains the main cutting/polishing and processing center as the Indians - and their noble families - have loved the green of emeralds for centuries, if not millennia).

Walking Around Bangkok Chinatown Chinese New Year

Walking around Bangkok's Chinatown at Chinese New Year...

Now you can perhaps understand why I can really get annoyed when I hear people say that the ‘Thai’ or ‘Asians’ are to blame for all these ‘fake gemstones’ in the market and that they hide this information when innocent buyers want to buy a ruby or blue sapphire.

Complete nonsense! The Thai saw a demand in the market, saw that others besides just celebrities and royalty wanted to be able to wear rubies and blue sapphires and found a solution that created permanently good blue sapphires and rubies by improving their heat-treatment.

And when I go to Bangkok to buy colored gemstones, I - and any gem buyer - will always ask whether the stones I’m looking at have been treated (when I know this particular type of stone may have undergone heat-treatment which is a very normal question to ask and to which you’ll get a perfectly honest answer. Everybody knows there that those heat-treated stones, such as rubies and blue sapphires, will be less expensive than the untreated ones. A ruby and sapphire vendor will most likely only have a few untreated gemstones anyway! The majority of his or her goods will consist of heated stones (except for very high-end dealers who only sell the best untreated rubies and sapphires). Great, because of this more people have a chance to buy a ruby or blue sapphire.

Now I do notice that in the Western market, jewelers - far away from the mining and main trading areas - who sell these stones set in jewelry to the ultimate consumer don’t always know whether the stones have been heated or not OR they may prefer not to pay too much attention to it because they fear the negative effect it will have on a potential buyer.

My advice … don’t buy loose gemstones if you don’t know about the stones' history. Read on to find out more about what to ask before you buy, especially when it comes to the more expensive stones, like rubies and blue sapphires!

Eva Gems and Jewels Pro-Tip

Pro Tip: What to Ask When Buying Your Own Gemstones or Gemstone Jewelry?

How can you protect yourself? Ask these questions and compare multiple jewelers or gem dealers for similar gemstones.

1. First ask: is this stone natural or synthetic? (So let's assume here we're talking about a stone that can be a loose, unmounted stone or a center stone set in a ring for instance).

2. If they answer the stone is natural: great → go to point 3.

If they answer synthetic: leave the store (unless you are happy with a fake gemstone for a cheaper price. Side note: synthetic diamonds are the exception to this rule and are actually not cheap at all because the process to make larger synthetic diamonds is time-consuming and costly). 

3. Then ask: has this stone been treated?
Now listen very carefully. Some jewelers may simply repeat: ‘no, the stone is natural’ and look at you as if you're nuts because they feel they just answered the same question before.
Remember most jewelers are not gemologists and they may not know that you’re now actually asking another question.

In that case, insist, keep smiling and say: ‘yes, I know it’s a natural stone, great, but I just want to know if the stone has been treated at all? So, was it heated for instance?’
Then they’ll get you’ve done some research and they’ll either be able to give you a better answer, get a more senior staff member or someone who has studied gemology to help you out or they may give you a certificate to look at.
If not: leave the store and go to the next.

4. When they tell you the stone is either
(a) natural and treated or
(b) natural and untreated (and thus more expensive):
know that today it is a safe practice to ask for a lab certificate on any ruby or sapphire or emerald purchase over $1000.  
For stones of lesser value or other stones than these, I wouldn't ask for a certificate and they probably won't have one either. There are exceptions again... there can be equally high value gemstones besides these 3, such as spinels, certain tourmalines or garnets that can also be sold with a certificate. 

5. The certificate should:

- come from an internationally reputable gem lab, such as Gübelin, GRS, GIA, SSEF, AIGS and NEVER from a small, local lab.

- state 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-treatment: don’t accept that and ask to see another stone or leave.

- note that 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.
Burma and Sri Lanka are desired origins for gem collectors and hence the stones will be even more attractive.

To sum up, know that heated rubies and blue sapphires are not fake at all, they are natural stones that have undergone a heat-treatment which is very normal for these stones.
And it’s partly your job to do some research and enter a store prepared with some questions, particularly for an exquisite product like this.

Even better, go to a store with a good reputation or a gemologist who can explain these points to you and guide you along the way so you can be sure you get the quality stone you want that suits your budget and personal preference.

If you were to buy a sports car or piece of art, wouldn’t you study a bit how the car works, where it was made and how, what makes it special, how much extra it would cost to get it in a special color or some other special feature you’d love? AND isn’t this part of the fun too?!

To know how to buy loose gemstones and understand more about these special products, their craftsmanship, quality or background, is to appreciate and enjoy them more.

And if you’re not OK with any type of treatment AND you have a bigger budget, then go for a naturally beautiful, ‘untreated’ ruby or blue sapphire which is more rare in nature, therefore more difficult to find in jewelry (or as a loose stone from a gem dealer) and as such, more expensive when you do find one.

Good Luck!

Ask Eva more about how to buy colored gemstones and finding the right stone or gemstone jewelry for you.

See also: The Difference Between a Diamond and a Gemstone


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