Does anyone have any experience using UV light to help determine what a gemstone is and whether it is synthetic or not in conjunction with the RI of the stone? The color is as follows:
GWLAb: Vivid Purple
GIA: Medium dark, Moderately Strong, Purple
This particular stone is supposed to be a purple sapphire.
The following is what it looks like under short wave UV light from my UV light cabinet.
The following is what it looks like under long-wave UV light in the light cabinet.
The RI is 1.768
Is this synthetic?
After posting this, i found the following article:
I therefore think the stone is a natural heat treated sapphire. Please let me know your thoughts.
I found straight growth lines. Using UV is also much faster when going through many gems. I normally receive about 800 stones from suppliers at any one time and I have to quickly sort through them. Then i go through the gemstones I am interested in in more detail. Then i usually have five days to fully inspect the gemstones before i have to either pay for them, accept them on consignment, or return them. Using UV is a very fast method of quickly sorting through the stones.
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I forgot that I have an extensive library of synthetic corundum… so here is a photo of one of the stones i’m trying to identify next to a small synthetic sapphire.
it reacts to short wave UV and is totally inert to long wave UV. Below is the photo of SWUV.
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Are you sure that corundum is synthetic? Looks like a natural reaction… kinda far out of the photo though… I thought synthetic would look more like glowing neon. (Just thinking out loud here) Learning as well. I don’t have a SW UV Light. Only long. Need to get one. = )
The small one sapphire on the right is synthetic for sure. I bought it as part of a corundum and spinel sample set from a manufacturer of synthetic corundum and spinel so I could do side by side comparisons like this.
The set includes ever color of corundum and spinel that they produce in 1ct rounds. I think there are 36 stones in the set if i remember correctly and cost about 30 USD. I bought them as part of a shipment of melee side stones i bought for our company. All gem grade stones that could be set into jewelry if you were so inclined to use them for that purpose.
I highly recommend getting a sample set from a manufacturer to go into the uv light box. My light box has SW uv and low uv and shuts out all ambient light. Not too expensive either, i think it cost about 200 USD with shipping and taxes.
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