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»  » 20 questions regarding spinel as engagement stone
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20 questions regarding spinel as engagement stone |
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| P: 10/25/2004 6:56:06 PM | |
raddygast Cut Rock Total Posts: 179 Last Post: 12/4/2006 Member Since: 10/20/2004 |
Ok, for various reasons I am leaning heavily towards spinel (most important of which is, for an equivalent quality fine ruby, I'd have to sell myself on the streets for a year to be able to afford it). I have some questions, though. 1) Hardness. I've seen the moh's scale for spinel quoted at 8, 8.5, 7.5, even 7. Which is it? Lots of places tell me they'd never recommend spinel because it is simply not a "lifetime" stone like diamond or corundum. Is it really that much softer? I was hoping it'd be hard enough to be set in something like a half-bezel at least. 2) Naturalness. Is there TRULY no treating process for spinels? I'm not referring to filling it with oil or fixing fractures (which I understand they sometimes do), I'm talking about color enhancement. I'd just like to hear that if I go with a fine colored spinel, the color was 100% produced by mother nature. 3) Rarity. I'd like to be able to say something like "spinel of this color is actually more rare than ruby." I've heard that, but I think it may be way off the mark. What is the reality? Can someone explain this bit to me? This is probably the most complex of the questions. I understand that spinel is MgAl2O4 while corundum is Al2O3. And spinel grows in the same deposits, and once the Magnesium is depleted corundum forms. I've also read that corundum itself is not very rare, certainly much more abundant and common than spinel. But gem-grade corundum is rare. Does this mean that gem-grade corundum is rare, or that gem-grade non-treated corundum specimens are rare? Also, I've heard that "fine colored spinel" is sometimes harder to find than "fine colored ruby" but it's much less expensive. I have no problem knowing that spinel is cheaper -- this is more of an issue of marketing and market demands and the timeless cultural history of the word "ruby." But is it really rarer? I thought maybe this was so because there was no way to enhance the color, whereas with ruby there is. But still, heated rubies of extremely fine color are still damn expensive. So is this "spinel is rarer than ruby" saying made on the assumption that we're comparing spinels to treated rubies? Because if it were untreated vs. untreated, isn't fine ruby infinitely more rare? I just wanted to get some of the facts straight. I love the look of this stone and was hoping to know more about it, scientifically and distributionally speaking. Is it actually a great "bargain" precious stone whose value in the gem trade is grossly underestimated at current market prices? Or is it just a cheap "ruby alternative" for ghetto consumers like myself? |
| Posted: 10/25/2004 6:56:06 PM | |
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There are 4 replies to this message. There are 4 replies on this page. |
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| P: 10/25/2004 7:06:57 PM | |
Richard Hughes Cut Rock Total Posts: 320 Last Post: 10/14/2008 Member Since: 9/27/2004 |
Here goes: 1. The hardness of gem spinel is 8 on Mohs' Scale. That's harder than emerald. If emerald is okay for jewelry, then so is spinel. 2. Spinels may be oiled. Rumors regarding heat treatment of some colors have existed for years. I've yet to see any hard evidence. 3. The top color of spinel (red with no garnety or pink overtones) is exceedingly rare, but so is a top ruby. Certainly the lesser flavors of red spinel are more common than those of ruby. I can easily lay my hands on a cleanish deep red spinel of 10+ carats. Not so for ruby. Bottom line: A fine ruby and a fine red spinel are both rare. Ruby is more valuable because... a. It is harder and less brittle. b. It tends to hold its color better than red spinel in a variety of light sources. Hope that helps ;-) Richard W. Hughes |
| Posted: 10/25/2004 7:06:57 PM | |
| P: 10/25/2004 7:13:09 PM | |
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raddygast Cut Rock Total Posts: 179 Last Post: 12/4/2006 Member Since: 10/20/2004 |
What I've heard is that emeralds are definitely not good for engagement stones unless in a very protective setting, owing to their brittleness. I've also heard that the mohs' scale is non-linear, so I was hoping to know if there is a significant difference between emeralds and spinels such that spinels are quite a lot more durable (but obviously not as indestructible as rubies). What about the actual rarity of the mineral, or rather the gem-quality rough of the mineral (vs. corundum)? I appreciate your comments about how spinel doesn't hold its color that well, I'll keep it in mind.
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| Posted: 10/25/2004 7:13:09 PM | |
| P: 10/25/2004 7:23:37 PM | |
Bertrand Ideal Rock Total Posts: 622 Last Post: 8/17/2009 Member Since: 7/13/2004 |
Well about the rarity vs rubies thing - have you been to the AGTA consumer site? Click below to find out - Spinels --------------------------- |
| Posted: 10/25/2004 7:23:37 PM | |
| P: 10/25/2004 7:28:10 PM | |
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Richard Hughes Cut Rock Total Posts: 320 Last Post: 10/14/2008 Member Since: 9/27/2004 |
The brittleness of emerald can be a problem. I once dropped one from about one foot distance onto a glass desktop and had two opposite corners break off (I quickly got rid of the glass tops on all our lab tables). And yet I have a friend who has a gorgeous Colombian sugarloaf cab that he has worn in a ring daily for decades without problem. Yes, Mohs' Scale is not linear. The difference between corundum (9) and diamond (10) is greater than talc (1) and corundum (9). But spinel is plenty hard enough to be worn as a ring. Indeed, my colleague, G., wears a fine Mogok red almost daily in her wedding ring and it looks terrific. As for rarity, didn't I answer that in my last post? I would respectfully disagree with the AGTA website. The widespread treatment of ruby has distorted the rarity equation. Fine untreated rubies are exceedingly rare, particularly over 2 cts. Richard W. Hughes |
| Posted: 10/25/2004 7:28:10 PM | |
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