How to detect synthetic spinel from natural spinels

One of the most difficult and common things in today’s Gem and Jewellery business is to detect Synthetic from Natural Spinels. How to find it for buyers of Natursl spinels to make sure they are not buying the wrong gemstones.

1 Like

The RI is often a little higher, but not every time
The composition is not exactly the same, but I can’t analyze it. Maybe a spectrometer could be helpful
I prefer to buy slightly included stones, preferably rough, and identify natural inclusions. So so beautiful anyway

Long wave UV light makes synthetics glow strongly and lines of small gas bubbles, often curved are another sign. Flux inclusions and curved growth lines might show with good magnification.
Green spinel is rare so careful buying one. Blue spinel is a common one to synthesise

1 Like

Both the above, and also the presence of crosshatching in the crystal under magnification.

But your right, this can be a tough one, and the blue colours seem to be the most commonly found synthetics.

1 Like

I’m pretty sure the spectroscopy for natural and synthetic spinels is different enough that you could make a determination that way. The Sisk Gemology Reference has fairly complete scope references in both diffraction and prism spectrums for several different colored spinels. The Sisk set is expensive, but worth it because it has almost complete info for just about any gemstone you need or want to look up. Also, Shumann’s books have comprehensive spectroscopy info, but you need to have knowledge on how to read them, he just gives bands of absorption info. The Sisk reference shows color pictures. It’s the primary reason I bought the reference.

1 Like

I have been collecting Spinels for many decades, since I was a student and that was all I can afford. If anyone have clients who can afford and would like to make into stunning necklace and bracelet, a ring or ear rings, please contact me, Thank you. I sent one out to GIA and have a certificate, they are very close deep and bright red as Rubies. From 1.2- 2.2 Cts etc.

I agree, Red Spinels and Rubies are so closed in colors esp, in deep red. Rubies in Asia are also popular in soft pinks or purplish pinks which are more affordable. I trusted GIA to send a sample there to test, most of the time, they are glass filled and heated which are more acceptable these days because of limited supplies. The mines in Thailand which was once very popular selling Siamese Red Rubies, now all vendors are complaining it is very hard to find Rubies. The situation in Myanmar is not good, look like the millitary will be ruling for many more years if not decades. It would be very rare to see Rubies and Jades or Sapphire coming out from Myanmar.

One of the ways I have of separating synthetic from natural spinels is by immersing them in high RI fluid in order to see more clearly into the stone. I think synthetic spinel also have curved straie like corundum, and it’s easier to see the straie under a microscope using the immersion technique. I use cedarwood oil because it is easy to obtain and non-toxic. I use perfume-grade cedar wood oil.

I also purchased a large selection of synthetic spinel so I could do side by side comparisons under UV light in my light cabinet. I also use them to compare the stones I’m considering purchasing from suppliers to ensure they are natural and not synthetic.