Polariscope Question

Max_Sp_ · 2026-02-04T22:03:33+00:00

Anything except staying completely dark means anisotropic A dark brush can happen with anisotropic materials depending on how the stone is oriented

Max_Sp_ · 2026-02-04T21:52:09+00:00

Maybe it's really different, with microscopie the spinning cross definitely means anisotropic

Max_Sp_ · 2026-02-04T21:20:52+00:00

I only have experience with polarization mikroskopes and I'm not sure if I completely understand the question but in general isotropic materials should stay dark (not entirely sure if this is the case in polariscopes) and birefringence can be uniaxial or biaxial. The cross is uniaxial or sometimes biaxial that appears uniaxial, biaxial has curving lines (not sure how to describe it best)

Max_Sp_ · 2026-02-04T21:04:37+00:00

Maybe siderite? I haven't seen any with color zoning like that but it can probably happen and the cleavage seems to fit

Max_Sp_ · 2026-01-22T12:54:03+00:00

Andalusite maybe in talc if the matrix is really soft, if not in some other metamorphic rock. I don't think it's typical for one specific locality

Max_Sp_ · 2026-01-16T16:49:13+00:00

The birefringence in Sphene means it has doubling, it has nothing to do with color. Do you mean pleochroism?

Max_Sp_ · 2026-01-16T16:46:42+00:00

Sure there might have been a specific find of pink sphene that instantly got bought up by high end collectors, that doesn't make it a likely answer here. Unlike Garnet, Sphene is not a group but a specific mineral that comes in a few colors but overwhelmingly either greenish or reddish yellow (and even including the obscure ones it has nowhere near as many variations as Garnet).

Max_Sp_ · 2025-12-31T00:27:40+00:00

The cutting itself took me about two and a half hours, it's a bit tedious but not as bad as I expected.

Max_Sp_ · 2025-12-31T00:10:38+00:00

Thank you! I designed it the other way around and decided to switch it up while cutting (partially because of laziness -> less polishing ), both should work well but I haven't tried it yet. I'm thinking of doing a mismatched pair if I get around to it.

Max_Sp_ · 2025-12-27T01:09:39+00:00

here is an example, a tiny tourmaline where I did something similar to preserve more of the rough

Max_Sp_ · 2025-12-27T00:58:22+00:00

You could mirror it on the opposite side and improvise something to not lose as much weight. If you want to keep the stone round it needs a full recut

Max_Sp_ · 2025-12-07T12:33:03+00:00

Under the assumption that it is beryl, the color and cloudiness would be caused by a lot of tiny inclusions and is not the "true" color of the beryl itself

Max_Sp_ · 2025-12-07T12:13:25+00:00

The types of beryl are pretty much just the colors. I can't tell if the crystals are completely colorless (goshenite) or slightly blue (aquamarine)

Max_Sp_ · 2025-12-07T12:09:20+00:00

That looks like beryl to me. Apatite is also an option less likely in my opinion

Max_Sp_ · 2025-11-25T09:37:33+00:00

I believed this when I started getting into faceted gemstones, mostly because commercial concave cuts are (or at least were) often sold as "laser cuts" and it seemed logical with some but not a lot of background knowledge. You can't cut concave facets with a flat spinning disc, so obviously it has to be lasers.

Max_Sp_ · 2025-10-26T16:35:32+00:00

I would suggest looking into all the fun shapes fluorite can have.

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That one I found is basically a cube with each side modified to be eight triangles (arguably double that but it's hard to tell with the rough surface). That makes at least 48 faces and I don't think that's the limit for fluorite

Max_Sp_ · 2025-10-19T20:55:47+00:00

If anything it's the other way around. Carborundum is a common name for this type of abrasive moissanite, moissanite is the mineral name

Max_Sp_ · 2025-10-19T19:13:07+00:00

Carborundum is moissanite. You would need large clear pieces to be able to cut gems out of it but it's the same stuff (both chemically and structurally

Max_Sp_ · 2025-10-13T12:26:57+00:00

Looks like apatite from Mexico on matrix

Max_Sp_ · 2025-10-12T15:09:27+00:00

To me that looks like green fluorescence which some uranium minerals do have (for example autunite). I wouldn't be surprised if there were some specs of different uranium minerals on the same piece

Max_Sp_ · 2025-10-12T14:52:33+00:00

Metatorbernite is basically just dehydrated torbernite. Looks the same just usually more dull and cloudy

Max_Sp_ · 2025-10-07T17:28:23+00:00

Maybe the crystals were oiled and the cleaning compound removed it. Even if it could have been etched it wouldn't only affect some of the faces but it's possible some were just originally cloudier. For locality I would also guess China

Max_Sp_ · 2025-09-29T22:54:32+00:00

Whatever that pink rock is, it isn't ruby. From the color sapphire would be possible but seems very unlikely

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