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- Aug 29, 2003
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There are a few spinels and a couple of detailed threads about them.
I like how the spinel story is told by Richard Hughes on Pala's pages HERE.
If I had to describe it in short... it is a gem very close in both chemistry and appearance to gem corundum of which ruby and sapphire are different colors. Just like corundum, spinel is most precious when blue or red and the respective colors are very similar to ruby and sapphire. Spinel is only subtly softer than saphire - not a significant difference for jewelry use. Spinel is very subtly brighter than sapphire and the colors are more consistent if you wish (i.e. sapphire is sometimes visibly dichroic spinel not).
Most of the time spinel is talked about in comparison to sapphire - just like I started. There are practical differences that get less note than the physical likeness. For once, good luck finding fine blue spinel - the color is very rare, allot less common than blue is for sapphire. Even the equally precious reds (from orange tinged 'flame' color, to saturated pink) are more common. The better blue color is associated with cobalt content - but I am not sure this chemical addition is indispensable for attractive blue color. Probably not - especially for the violetish blue.
Fancy color spinel (not red or blue) is very overlooked - IMO. Probably because there are not enough stones to make a name for themselves... Who knows. Practically, orange and light pink spinel, and violet spinel could have a better fate and is quite inexpensive.
The usual fault of spinel colors - when there is any - is being too gray. Some are arguably nice curiously looking gunmetal color gems - but these have few fans and should be among the most inexpensive natural stones faceted.
It is very possible to find a few blue spinels that truly look like fine sapphire. Well, that you have found a rarity that may not come again in years!
Perhaps the one down that link is not the finest - but given the description, price and the little I know about the shop it should be quite a bit better than average and would not expect a grayish stone. But the looks of a dark blue sapphire of unexpected clarity and brilliance - heated dark blue sapphire is often muddy - spinel not so.
Treatment? None. Spinel does not respond to heating. Very rarely, some fine red ones are clarity enhanced just like ruby is. But this is extremely unusual.
If you like pink, pink spinel is a marvel!
On Pricescope, try a search for 'Namya' for some nice story about a recent find of outrageously colored spinel. There is more about it on the AIGS website...
Probably every jeweler could find some spinels from their suppliers to show you if you ask for it. From those posting here, Gemsofearth.com lists nearly only fine spinel!
Richard Homer has two blue spinels on display. One of impressive color (well, for me at least).
And since a post would not be quite OK without a picture, how about this:
The crystal above makes a great point about how closely related spinel and sapphire are - it grew in two layers - the core is corundum (purple sapphire), the outer layer spinel. It takes a slight modification of growth conditions to slip from one to the other.
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