playing with Chelsea filter

[Arkteia]

It still can be useful! I first read about them in Matlin's book, then I decided they were almost obsolete given the abundance of synthetics, then per advised of experts, got one. I used it on my stones, mostly for fun, but some of my spinels, to my surprise, turned red under the filter. At first I thought they were synthetics, even called off a sale of one of them, but given vendors' reputations, I I decided to send them to AGL. Both came back as cobalt-bearing. I was never searching for cobalt-bearing spinels, but it is nice to know that I have two. I do not know how common they are, though. Photos to follow.

 

[Arkteia]

This is the smaller of the two, I do not have the approximate stats, per size, it is over 1 ct

[URL='https://www.pricescope.com/forum/download/file.php?id=247420']https://www.pricescope.com/forum/download/file.php?id=247420[/URL]

 

[Arkteia]

And the second one I posted recently, I really like it...

So I do not know whether the mere fact of a spinel being cobalt-bearing carries additional value, or it should not, if the color is less than perfect. It is my understanding that the content of cobalt may also differ in different stones, too, and depending on it, you may see a very saturated stone (my first one - it has significant extinction but I am not going to recut it), or less saturated one. I would not be surprised if cobalt=bearing stones could appear grey as well. Can someone, please, comment on different colors one can see in cobalt-bearing spinels?

 

[chrono]

I think the amount of cobalt versus iron plays a role in how gray / intense the colour of the spinel is. I've seen some amazing cobalt bearing blue spinels and some that aren't so nice.

 

[Lee Little]

Are these spectacular colors of Spinel from Viet Nam? Best regards, Lee

 

[JewelFreak]

Arkteia, that is one of the most luscious blue spinels I ever saw! A real true beauty. It is a higher concentration of iron, isn't it, that makes one more gray? Anyway, do you have plans for it yet?

--- Laurie

 

[Dioptase]

I do not know how common they are, though.

They are rare and sell for a premium.

 

[Arkteia]

Chrono, thank you for your support and explanation! I, too, thought that it is the content of cobalt that matters in the overall appearance.

Lee, I do not think they are. I did not ask AGL to determine the origin, for one of them, the seller stated it was, Tanzanian, as to the other one, I just did not see this piercing neon quality that would justify additional investment.

 

[Arkteia]

JewelFreak, thank you, but your stone looks much prettier. I have no plans for my stones, yet. One of them will probably stay in my collection, and the other one may be mounted, but later, since I have three stones in work...

 

[Arkteia]

Dioptase, thank you. Now I have two proven cobalt-bearing spinels, AGL certificates have just arrived. 1.22 ct, and 1.67 ct. stones. I shall not guess the cost of these stones. It surely was fun to see them glow under a filter. It is also interesting to see the difference in color.