Certified Gemologist

A Primer on the 5 Things to Know before Committing to a Purchase

Get guidance from a certified gemologist and become well-versed in the basics of colored gemstones. 


Where diamonds have a globally accepted grading system and standardized certificates, colored stones have no such thing. On top of that, color is subjective which makes color stone grading more daunting. 

Learn these 5 best practices from a certified gemologist so you can confidently buy loose gemstones - without the overwhelm. 

1.Get To Know The Names Of The Best Quality Gemstones

You may be surprised to know that there are other fine quality gemstones besides the well-known emerald, ruby, and blue sapphire. 

But what other green stones can you think of besides the emerald? Did you know there are about 4 to 5 other high-quality green gemstones out there? 

The exquisite grass-green tsavorite garnet can even easily beat the emerald in quality… Other fine quality green gems are demantoid garnet, green beryl, lagoon or neon mint tourmaline, peridot, and spheres. 

The same applies to the red hue: can you name other high-quality varieties besides the ruby? (Like red spinel, reddish tourmaline and garnet...). 

Do you know any yellow gemstones, electric blue ones or even neon pink ones?

It pays off to do some research online or buy a book on colored gems so you’ll be aware of the high-quality gemstones out there. Your gemstone dealer or jeweller will thank you for it as you’ll be able to articulate what you want and the colors you like. 

 2Learn The Difference Between Natural, Synthetic, Man-made, And Fake Gems

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.

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. There exist, for instance, synthetic diamonds, rubies, and blue sapphires. These synthetic stones you can call the 'fakes'. There is nothing wrong with them as long as you’re aware of it and you paid a lower price. 

Man-made gems (or stimulants) are the same as synthetic gems - with a subtle yet important difference - as they don’t have a natural counterpart. Synthetic gems always have a natural counterpart, while man-made gems are basically invented by humans but don’t exist as such in nature. Examples are the man-made diamond simulants YAG and GGG.

Fine-quality natural gemstones are the rarest and will be the most valuable of all of the above. It’s good to know about these distinctions as it’ll make you ask the right questions and it’ll make you appreciate a highly valued natural gemstone even more. 

3. Be Aware Of Gemstone Treatments

A treated gem is any gemstone that has been altered by humans, beyond ordinary cutting and polishing.

Treatments are very common in gemstones, including diamonds, yet most consumers are not aware of them or they assume it has a negative connotation. This is undeserved for many treatments.

The reason treatments exist is simple: without gemstone treatments, there wouldn’t be enough gemstone quality stones in nature to satisfy the jewelry demand in the world… 

For instance, 95% of natural rubies and blue sapphires have been heat-treated! A fully acceptable treatment in the gem market. 

Likewise, most emeralds are oiled and fracture-filled. Then there exist other treatments like irradiation (also accepted for certain stones) and lattice diffusion (which most reputable gem dealers don’t accept). Also, diamonds can be subjected to certain treatments, such as laser-drilling and fracture-filling

Many treatments get lumped together under the blanket term “enhanced.” But that way, you still don’t know what specific type of treatment has been carried out and also, if it’s acceptable to a reputable gemstone dealer or not. Try to get a specific answer. 

And as treated stones are less expensive than a similar, untreated gemstone and some treatments are simply not acceptable to a good gem dealer, it’s important to know about them and to ask your gem dealer about his policy on treatments. 

4.Learn To Roughly Judge A Colored Gemstone’s Appearance 

The most important feature that determines the beauty and value of colored gemstones is color. Judging color is done best by comparing similar colored gemstones together.

Our memory of color is short. Only when you see a few colored stones of the same species & color, of a similar carat weight and shape together, will you be able to pick the best stone from the lot. 

Color grading consists of 3 elements: namely the grading of (1) the stone’s hue, (2) saturation and (3) hue. 

The hue means that you need to assess the stone’s main and secondary color. So a stone can be orangey-red or greenish-blue for instance. 

Saturation is about judging the vividness of the color or the lack of color. Generally, the more vivid the color, the more valuable a stone will be. 

Tone relates to the presence of blackness in a stone. The medium tone is usually good. 

Besides color, you can look at the clarity and transparency of the stone, the symmetry of the cut, if it sparkles a lot: all indications of a higher quality gem. 

This means you need to go to several jewelry stores, gem dealers or fairs to practice your eye!

5.Protect Yourself With A Gemstone Certificate

Today it’s a safe practice to ask for a lab certificate on any ruby, sapphire or emerald purchase over $1000.  

For stones of lesser value, I wouldn’t advise getting a certificate. Besides those famous stones, you can also ask for a certificate for high-quality spinels, certain tourmalines or garnets - provided they have a significant value. Your gemstone vendor might charge a fee to facilitate this.  

Ensure that the certificate:

  1. comes from an international reputable gem lab, like Gübelin, GRS, GIA, SSEF, AIGS and NEVER from a small, local lab

  2. states the name of the stone and the treatment, if any

  3. - if you’re a gem connoisseur who is keen to know this - states the origin of the stone.   

Origins like ‘Burma/Myanmar' or ‘Ceylon/Sri Lanka’ are desired origins for gem collectors and those stones will be sold at a premium. 

I personally don’t care about origin so much as long as I have a very beautiful gemstone! So, I’d leave the famous origins (and their extreme premium prices) for the connoisseurs who almost value the provenance more than the actual beauty of a gem.  

To sum up, after you’ve done some research on your own, feel free to ask the vendor’s policy on the above, especially on gemstone treatments. 

Don’t be intimidated and try to get a specific answer! If that’s not possible, go to another vendor. An educated consumer should be welcomed by a knowledgeable gem dealer. 

Did you recently purchase a gemstone? What questions did you ask before finalizing your purchase? Were you happy with the answers? Tell [us/me].

And if you like personal guidance from a certified gemologist, gem dealer and jewelry designer specialized in rare colored gems, Ask Eva from Eva Gems & Jewels


Author's Notes/Comments: 

Eva designs ready-to-wear jewelry as well as seeking out special gemstones for clients to create the jewelry pieces of their dreams.

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