Colour change stone

[Shiny Black Cat]

I know l should test this stone in a lab, but l can't reach gem lab at the moment . I have it for a while, loose stone, find from second hand store and managed to capture its colours. It's blue greenish in daylight, green in LED light, purple redish in incandescent light,purple blue in mixed light, glows weak red in black light, 3ctw, no visible inclusions. Can l get your opinion on this stone?

 

[Bron357]

If it’s got no inclusions it’s most likely lab created.
No one can tell from photos unfortunately, you’d need to send it to a lab for confirmation.
If you are able to calculate Specific gravity at home ( you need accurate scales to 0.000 grams and look on You tube for how to do it) you might be able to rule in or out possible gems.
Be aware that lab grown gemstones have the same SG as the natural from the earth gemstones they are mimicking.
Alexandrite is 3.70- 3.78
Colour change Garnet is 3.89
Fluorite is 3.175 - 3.184

 

[lovedogs]

Agree with bron. Given the size and lack of inclusions it is likely synthetic

 

[Voodoo Child]

As others have said, it’s most likely a synthetic Alexandrite. An eye clean three carat Alexandrite with that level of color change would be worth well over $100,000.

 

[Shiny Black Cat]

If it’s got no inclusions it’s most likely lab created.
No one can tell from photos unfortunately, you’d need to send it to a lab for confirmation.
If you are able to calculate Specific gravity at home ( you need accurate scales to 0.000 grams and look on You tube for how to do it) you might be able to rule in or out possible gems.
Be aware that lab grown gemstones have the same SG as the natural from the earth gemstones they are mimicking.
Alexandrite is 3.70- 3.78
Colour change Garnet is 3.89
Fluorite is 3.175 - 3.184

thanks

As others have said, it’s most likely a synthetic Alexandrite. An eye clean three carat Alexandrite with that level of color change would be worth well over $100,000.

l am learning about alexandrite, so would like to know what metod was used to produce this stone?

As others have said, it’s most likely a synthetic Alexandrite. An eye clean three carat Alexandrite with that level of color change would be worth well over $100,000.

 

[Bron357]

Aside from natural garnet and fluorite which are also colour change gems, there are a number of types of man made gemstones that mimic the colour change of Alexandrite.
There is a recent modern synthetic glass that does have spectacular colour change, often sold on shopping networks as Zandrite. It’s the cheapest version to buy. It’s the same hardness as glass so not very durable especially in a ring.
Then there’s man made colour change corundum. More recent types mimic the correct colour change, the older version, very popular in huge sizes in cocktail style rings from the 60s / 70s / 80s arent accurate with their colour change basically a pinkish purple colour that sometimes looks a bit bluish purple. This is slightly more expensive. This is popular as with a hardness of 9 it will wear well over time.
Then theres hydrothermally grown Chrysoberyl. This is the same chemical composition as natural Alexandrite except grown in the lab. This is expensive to buy, for a man made created gemstones, because it’s a specialist product and expensive to produce. A vendor called Tairus Gems sells a number of hydrothermally produced (lab) gemstones.

 

[Shiny Black Cat]

Aside from natural garnet and fluorite which are also colour change gems, there are a number of types of man made gemstones that mimic the colour change of Alexandrite.
There is a recent modern synthetic glass that does have spectacular colour change, often sold on shopping networks as Zandrite. It’s the cheapest version to buy. It’s the same hardness as glass so not very durable especially in a ring.
Then there’s man made colour change corundum. More recent types mimic the correct colour change, the older version, very popular in huge sizes in cocktail style rings from the 60s / 70s / 80s arent accurate with their colour change basically a pinkish purple colour that sometimes looks a bit bluish purple. This is slightly more expensive. This is popular as with a hardness of 9 it will wear well over time.
Then theres hydrothermally grown Chrysoberyl. This is the same chemical composition as natural Alexandrite except grown in the lab. This is expensive to buy, for a man made created gemstones, because it’s a specialist product and expensive to produce. A vendor called Tairus Gems sells a number of hydrothermally produced (lab) gemstones.

thank you

 

[PrecisionGem]

If it’s got no inclusions it’s most likely lab created.
No one can tell from photos unfortunately, you’d need to send it to a lab for confirmation.
If you are able to calculate Specific gravity at home ( you need accurate scales to 0.000 grams and look on You tube for how to do it) you might be able to rule in or out possible gems.
Be aware that lab grown gemstones have the same SG as the natural from the earth gemstones they are mimicking.
Alexandrite is 3.70- 3.78
Colour change Garnet is 3.89
Fluorite is 3.175 - 3.184

Specific gravity measurements take a very accurate scale, and the smaller the stone, the more accurate it needs to be. The SG set up needs to be well done too.
In the case of a 3 ct stone, if you scale reads 3 decimal places, and the third place is read to 0.001 then even this is not accurate enough. For many scales the last decimal place is +/- 0.005 which could only be used on very large stones.

Lets look at the example of this stone. Assume the exact weight is 3 cts. which is 0.6 grams.

In water if it were Alexandrite it would weigh 0.44 grams, calculating out a specific gravity of 3.75.

But if our scale is accurate +/- 0.001 then we could measure:

0.599 in air
0.441 in water
SG = 3.791 which is outside the range.

If the scale is accurate to only +/- 0.005 then we could measure:

0.595 in air
0.445 in water
SG = 3.967

For small stones, you really need a scale that is accurate to +/- 0.001 ct to be useful. A scale of this accuracy is normally over $1000.