Marble(extreme opaque) corundum, beryl and other

[Procer]

Hey all.
A newbie here, I have being collecting colored gemstones for some years now, and I recently found this website, pricescope, while I was searching for clarification regarding the authenticity of a gemology company, a clarification that this site and its users provided, and great thanks for that. I have recently gone into the world of selling gems, not from my own shop, but from a trustworthy auction house here in my country. I do this for two reasons:
1. The general public, and myself, trust this auction house, and by the help of their experts I do not sell anything that is not what it seems.
2. I don't have any real education in gemologegy, I am self tough, so to speak, and I would never risk selling anything to anybody, that I could be something that it is not.
But in order to learn, you also sometime have to ask questions, and I have one for you, the users of pricescope. I is regarding whether or not the kind of stone showend in the picture actually can be considered to be gemstones? And is it called anything special? Or is there anything else worth mentioning about these type of stones? The picture is from my actual current action, but should not be considered and advertisement, but I would just mention it so there is no conflict of copyright.

 

[chrono]

I believe that if it is something made by nature with a crystalline property, it is considered a gemstone. The next question is with regards to the quality of the gemstone. I do not know what it is but it seems to be clarity challenged. As such, I do not think it will be worth much, despite its impressive size. What family of gemstone is it in?

The cut is rather interesting though since it appears to be a flat bottomed faceted stone? Unless it is upside down with a flat table?

 

[Procer]

It should be natural, according to the seller, and this is supposed to be red corundum, a ruby so to speak, but I hesitate, I don''t now, it just for me don''t seem right to call a stone like that a ruby, maybe it i s just me.
It is very clarity challenge, there is no way to see through it, even when exposed to heavy light from behind, it is less transparent then a block of marble.
It is of 152 carats, with and estimated( from the auction house) price at 1000 dkk/ 195.49$, so compared to size not that great a price( I have sold citrines that had much greater price to pr carat, weighing 23 carat and sold for 3000 dkk/ 586.48 $, because of the better clarity). And this red corundum is actually a rather small stone, in the total opaque category. I have seen them in the corundum family, both in ruby and sapphire, at a total massive carat weight of 5000 carats, and then the price is around 1000-3000 dollars, depending on the supposed family( you can all so find emerald like this in 5000 carat).

For me these kind of stones is more like an oddity, I have one but have sold most of the ones I have gotten in, t I actually think that there should be a separate category for stones of this type, because of its massive difference in size, color, extra material(inpurities), and clarity. Any thoughts on this?

 

[LD]

I hope you don't mind me being honest? I was sent 3 gemstones, purportedly Emerald, Ruby and Sapphire (very large) by an Ebay seller, as a freebie with another purchase. They're very pretty to play with but probably not worth much at all.,

 

[chrono]

Thank you for the explanation. A ruby is still a ruby but I guess this one is lower than even a commercial quality ruby. I really think the stone is worth terribly little, less than in the hundreds category. You''ll be hard pressed to find a market for these types of stones.

 

[Procer]

On the international market, yes it will be terrible hard to find anyone who wants to buy them, but here in Denmark, with the final crises, there are actual a pretty good flow. But I think that is kind of an unstable market. Within a short time, I figure that people will realize that these stones are not that great an investment item.

Oh yea and I just saw that I had forgotten to explain the cut on the stone, which is a crude oval cut, and on the photo it is turned upside. I should properly have given a photo on every side.

 

[morecarats]

Date: 9/29/2009 4:01:34 PM
Author: Chrono
I believe that if it is something made by nature with a crystalline property, it is considered a gemstone. The next question is with regards to the quality of the gemstone. I do not know what it is but it seems to be clarity challenged. As such, I do not think it will be worth much, despite its impressive size. What family of gemstone is it in?

The cut is rather interesting though since it appears to be a flat bottomed faceted stone? Unless it is upside down with a flat table?

You''ve given a definition for a mineral, not a gemstone. The term "gemstone" is a qualitative concept, often defined as a mineral which is beautiful, durable and rare. It''s obviously not a scientific concept, and a number of gemstones are not even minerals -- some are rocks (like lapis lazuli) and some have no crystal structure at all (such as pearl, amber and coral).

Even in the corundum family, very few specimens are gem-quality. The fact is nearly all gem-quality minerals are rare. But minerals are plentiful, and there are enough natural non-gem quality crystals around to keep eBay going for hundreds of years.

 

[chrono]

Date: 9/30/2009 9:45:03 AM
Author: morecarats
You''ve given a definition for a mineral, not a gemstone. The term ''gemstone'' is a qualitative concept, often defined as a mineral which is beautiful, durable and rare. It''s obviously not a scientific concept, and a number of gemstones are not even minerals -- some are rocks (like lapis lazuli) and some have no crystal structure at all (such as pearl, amber and coral).

Even in the corundum family, very few specimens are gem-quality. The fact is nearly all gem-quality minerals are rare. But minerals are plentiful, and there are enough natural non-gem quality crystals around to keep eBay going for hundreds of years.

You’ve found the word I was looking for: this is what I consider a non-gem quality piece.
Off-topic, is the term “gemstone” then rather subjective? I’ve seen many gemstones that are not durable and appear quite plentiful.

 

[Procer]

Good point, kind a like amethyst, not in the not-beautiful or durable part, but the plentiful part, there is plenty of amethyst to go around.

 

[Richard M.]

Date: 9/30/2009 9:45:03 AM
Author: morecarats

Even in the corundum family, very few specimens are gem-quality. The fact is nearly all gem-quality minerals are rare. But minerals are plentiful, and there are enough natural non-gem quality crystals around to keep eBay going for hundreds of years.

Thanks for the best chuckle of the day so far. So true! Consumers should not forget that minerals like corundum (ruby and sapphire) provide outstanding gemstones but also have their greatest use as sandpaper. It''s all a matter of quality.

Richard M. (Rick Martin)

 

[Harriet]

Morecarats,
Is that definition a bright-line one?

Rick,
If I had a penny for every inky corundum I see...

 

[morecarats]

Date: 9/30/2009 10:36:31 AM
Author: Chrono

Date: 9/30/2009 9:45:03 AM
Author: morecarats
You''ve given a definition for a mineral, not a gemstone. The term ''gemstone'' is a qualitative concept, often defined as a mineral which is beautiful, durable and rare. It''s obviously not a scientific concept, and a number of gemstones are not even minerals -- some are rocks (like lapis lazuli) and some have no crystal structure at all (such as pearl, amber and coral).

Even in the corundum family, very few specimens are gem-quality. The fact is nearly all gem-quality minerals are rare. But minerals are plentiful, and there are enough natural non-gem quality crystals around to keep eBay going for hundreds of years.

You’ve found the word I was looking for: this is what I consider a non-gem quality piece.
Off-topic, is the term “gemstone” then rather subjective? I’ve seen many gemstones that are not durable and appear quite plentiful.

I wouldn''t say the term "gemstone" is subjective, but the definition is certainly somewhat fuzzy. Some of the most famous gemstones -- think opal -- are not very durable at all, but they make up for it with their unusual play of color and rarity.

Some gems which are now plentiful, such as amethyst, were at one time quite rare. In fact amethyst was at one time regarded as a "precious" gem. It wasn''t until the mid-19th century when the huge deposits were discovered in Brazil that amethyst became a "semi-precious" stone. Indeed, the introduction of the term semi-precious apparently dates from that time.

These days the number of gem varieties being set in jewelry has expanded considerably. At one time a gem like sphene was regarded as too soft for jewelry, but these days people even set sphene in rings. The change is due, I think, to an enhanced appreciation of the unique properties of many minerals, techniques for making more protective settings, and an understanding by the consumer that certain gems are suitable for occasional wear pieces only.

 

[morecarats]

Date: 10/1/2009 12:57:48 AM
Author: Harriet
Morecarats,
Is that definition a bright-line one?

Rick,
If I had a penny for every inky corundum I see...

Definitely not a "bright-line" definition. Not only is the definition fuzzy, but it is constantly in flux. In the case of ruby, for example, high quality specimens have become so rare that a lot of lower quality material has entered the market to meet demand. Who would have thought that a fracture-filled ruby would be regarded as gem quality?

Fluorite is another case. It was always popular with mineral collectors, but was not really in use as a gemstone. Not only is it very soft but it has perfect cleavage. But it''s now popular in jewelry, especially for pendants, and I get many reports from jewelers who have suffered "bench mishaps" while setting fluorite.

Sphalerite is another interesting case. It''s a fascinating mineral with outstanding dispersion (especially in the lighter colors). But at one time it was never considered a gemstone, due it its poor hardness (similar to fluorite). Now there''s tremendous demand for it.

 

[Harriet]

Morecarats,
Thanks for the interesting historical snippets. I wonder if Turkish diaspore will be perceived as "beautiful" now that it has an exotic moniker. Perhaps defining "gem" is an academic exercise. I''m looking for a phosphophyllite, and am not fussed about the durability issue.

 

[chrono]

MoreCarats,
You’ve explained exactly what I meant with regards to stones like fluorite, sphalerite, heavily treated X stone, etc. You are very knowledgeable not just about gemstones but in its history as well.
Harriet,
Looking at JTV and the other jewellery cable networks, Turkish disapore or Sultanite seems to be rather popular.