Identification of Tanzanian multicolored rough stone Ruby/ Sapphire/ Spinel/ Garnet

Hi please help with indetification of very unusual gem. My friend bought it as Winza Ruby in Matrix specimen, but piece is multicolored. Red, purple, pink, orange, blue, green. Did you know its rare form of Sapphire or Spinel? Or even Garnet?
Sorry for quality of photos, its print-screen from video.

I would test the RI of this specimen which should help you narrow down the possibilities of what it could be, but I believe it is in fact a winza ruby. I am by no means an expert when it comes to rubys, but from the research I have done these colors you are noticing would be found in this gemstone. I would encourage you to do some research online of you havent done so already.

What makes you think that this may not be a winza ruby?

Looks like the typical hexagonal crystal. That would indicative of sapphire but not garnet. Really need RI for a definitive answer.

The other issue here is whether you are valuing this as a specimen or a possible cuttable gemstone. If you grind a flat on it to take an RI, its value as a specimen is seriously impacted. However this would give you the ability to polish a face on it and then get an RI. You could possibly hand hold it on a refractometer prism once you have a flat, but it’s hard to do that while you are bending down to look in the refractometer eyepiece, so you might need an extra pair of hands or a large lump of some putty-like substance like “blue tac.” Also bear in mind that even if this is a ruby or sapphire, value is negatively impacted if it is seriously included. I can’t tell whether that’s the case from your photos and you may not be able to tell too much, either. That’s another argument for cutting and polishing a nice window in it. Larger flat windows are a lot more difficult to cut and polish than small gemstone facets, but it just takes some technique and time, it is not impossible. When you can see into the crystal, you can assess it’s clarity better. You could also use an immersion fluid for that… -royjohn

Hi, always difficult to ID from photo’s but I would think it is a Winza sapphire just by the look of it, my suggestion would be to use an ultra violet light, if it is Winza it will fluoresce thanks

Spinel will also fluoresce.

We are seeing the orangey color in one photo and a pinkish red in another, yes?

Assuming that you rotated the stone for those two separate photos, and you used the same light source, you are likely seeing the phenomenon of dichroism. That would eliminate the garnet and the spinel and point to the likelihood of it being ruby.

1 Like

I am not able to see much definition in the rough material but do see one thing that is interesting. The blue/purple areas remind me of the cores of the ruby crystals of Mong Hsu, Myanmar (Burma) which are removed through heat treatment to improve color and clarity. As far as an RI reading goes, the piece you have is far too rough. What I do recommend is a test for specific gravity as corundum comes in at around 4.00. Also, check to see if you can detect the faint sheen of rutile needles on the surface where the light is nicely reflected. You can also check the difference in fracture luster as garnet is vitreous and corundum is sub adamantine. I hope that this helps you in your quest and invite you to let me know if you have further questions.
Brian Hudson GG (GIA)