Hello Everyone,
I was looking at a stone and it turned out that it was showing double refraction when seen under the polariscope, but when i checked the R.I. using polarizing filter the R.I. stayed constant at 1.77 no matter how i turned it....I guessed it was garnet showing ADR...but on checking in microscope the stone was showing rutile silk as seen in rubies...the criss cross hatches...I want to know can garnet have silk like inclusions of rutile...is there any way to confirm it is a garnet...the dichroscope showed no pleochroism and the it was inert to u.v so definately not ruby.. i cannot rely on the s.g. because the size is small and the error gets too large...can anyone suggest a better method of testing..
_________________ Exotic Gemstones: All Natural & Untreated
The Star Ruby Shop
Yep! That's the one Alberto...Distinctly similar...I was wondering how it is oriented in the hexagonal pattern when the garnets are from cubic system..at least i know that my stones are definately garnets!
_________________ Exotic Gemstones: All Natural & Untreated
The Star Ruby Shop
It may look surprising, but the cubic system is actually 'defined' by the fact that it has at least three axis with three-fold symmetry. (I think a fourth will always exist once you have found 3). If you spin a rhombic dodecahedron (a classic shape for garnet crystals) around, you can 'look down' on one of the points where 3 vertices meet, and you will see a hexagonal outline. Look 'down' at a point where 4 vertices meet, and you will see a square outline.
As an analogy, you can look down 'diagonally' at a cube from one of the corners down to the exact opposite corner. The outline will be hexagonal as well, with the 3 vertices joining the center point to 3 of the 6 ouline corners.
Sometimes garnets with rutile inclusions show bright reflective characteristics like this in darkfield illumination.
I've never seen this mentioned in ruby, but it may exist. Your observations are screaming garnet. There are some other simple tests to confirm, but I don't think it's necessary at this point.
Hey Keirkof sounds like your ready for that exam...are you sitting in June?
I hope you're right I made arrangements with Gem-A and Peter to sit in June in Arnhem. When I get back from three weeks off this Monday I should find my exam confirmation form in the mail pile. Then a fortnight later it'll be bizness time.
Yup the stone is garnet indeed and are showing A.D.R....i did check the angle and it turned out as mentioned...I even checked in U.V. Thanks for the info guys!!
_________________ Exotic Gemstones: All Natural & Untreated
The Star Ruby Shop
Users browsing this forum: No registered users and 3 guests
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot post attachments in this forum