corundum

[Bobby]

Hi i just wanted some clarity on differentiating between silk and growth lines in corundum.I mean theoretically i do understand but looking through a microscope im confused between the two.Posting a picture of a ruby under a microscope.Not very sure if they are growth lines or silk.it seemed very angular.Thank you.

[Barbra Voltaire, FGG]

Hello.
I think your pictures depict faceting abrasion on the surface of your stone, not internal characteristics.

[Barbra Voltaire, FGG]

Aso, note that I moved your post to CSI: Colored Stone Identification.

[Bobby]

Thank you for your reply.

[chrisP]

Silk in sapphires are usually rutile inclusions. Growth lines are not inclusions but evidence of the crystal's formation history. But you don't need a microscope for either. This can be determined with the naked eye. The one photo (single photo of a yellow 6 gram sapphire from Tanzania) shows needle-like inclusions if you look closely. These are rutile needles. The photo collage shows an 11 gram danburite crystal and a cat's eye cut from it. You can clearly see the parallel arrangement of the inclusions. The principle is the same for star corundums. The only difference is that the rutile needles are at an angle of 120° (?) to each other.
And, as Barbra already explained, your photos show scratches on the surface.