What are those lines?

[Gemmal]

Does anyone know what these lines are? I have just purchased an alexandrite and it is really nice. I was looking at it through a loupe and at a certain angle I can see these lines that sort of look like very fine grooves on a record. The stone does not have any grooves but it looks like it is inside of the stone. You cannot see it if you look at it from the top and have to angle it a certain way only in a certain lighting situation. Very interesting. Am really learning to love this stone.

 

[path914]

If the lines are truly inside the stone then they could be growth lines indicating the original crystal growth or possibly needles of another mineral such as rutile or hematite. Are all the lines in the same direction or do they intersect?

 

[Gemmal]

Definitely in the same direction. Wow thanks a million for the quick response. You guys are truly great.

 

[C Smith]

I have seen one early synthetic made with the pulled method that shows those types of internal lines. The lines were dead straight. If the lines are curved, flame fusion synthetic should be suspected. If the lines look like rain, suspect flux-melt synthetic. Was the stone sold as natural? Has a gemologist looked it over?

 

[Gemmal]

Yes, it was sold as a natural untreated alexandrite. Do you suspect synthetic. Bummers

 

[C Smith]

Date: 6/24/2006 4:40:01 PM
Author: Gemmal
Yes, it was sold as a natural untreated alexandrite. Do you suspect synthetic. Bummers

Not necessarily. I was just trying to help you cover the bases. It could very well be a natural characteristic in that example. How big is the stone? Can you post a pic? I''d love to see it.

 

[Gemmal]

lol this is really funny but I don''t know how to post pictures. the Alex is 3/4 carat and color change is from blue green to reddish purple. I think the lines are like very long rain drops. They are not curved. The lines do not reach the surface of the stone. What do you think are they growth lines or are they synthetic. I know, its is hard to tell without seeing it but I wondered why natural stones would have lines in them. For that matter why would synthetics have lines?

 

[C Smith]

There really is no way to tell for sure without seeing it, but rain inclusions are diagnostic for flux-melt synthetic, especially in the presense of near perfect color change. Once again, what I am envisioning may not be what you''re seeing. A pic would be helpful.

 

[Gemmal]

Thanks so much I will try to learn how to load up the picture if I can. It may take a while. In the meantime could you tell me what kinds of inclusions would be present in a real alexandrite? Also what would it look like. Thanks a mill and I hope you are having a super weekend.

 

[C Smith]

Have a look about halfway down this page for rain inclusion pics;

http://images.google.com/imgres?imgurl=http://www.yourgemologist.com/microscopes/micro4.jpeg&imgrefurl=http://www.yourgemologist.com/microscopes/microscope.html&h=184&w=193&sz=15&tbnid=4pErng6r5swiaM:&tbnh=93&tbnw=98&hl=en&start=1&prev=/images%3Fq%3Dalexandrite%2Binclusion%26svnum%3D100%26hl%3Den%26lr%3D%26newwindow%3D1%26safe%3Doff%26sa%3DG

 

[Gemmal]

Thank you. It doesn''t look at all like that. I wish I could explain it better. It looks like lots of thin lines. Like you got a paint brush and brushed it down the stone but it''s inside of the stone. Thank you again you are so sweet to help me figure this out.

 

[Richard M.]

Date: 6/24/2006 9:23:21 PM
Author: Gemmal
It looks like lots of thin lines. Like you got a paint brush and brushed it down the stone but it''s inside of the stone.

I''ve cut a fair amount of natural alexandrite and know most of its quirks. Without an actual image I can only guess, but I think you''re seeing a small patch of "silk": tiny bunches of parallel rutile crystals. They''re a common inclusion in faceted alex.

When they exist in sufficient quantity they can result in cat''s-eye stones with proper cutting. Unlike corundum where included rutile crystals cross at angles creating a star effect, they run in only one direction in cat''s-eye color-change chrysoberyl (alex). If a professional confirms rutile inclusions, that''s excellent proof of natural origin.

Richard M.

 

[path914]

Although it shows silk needles in corundum and not alexandrite, this page does have some good pictures that might help:

http://www.agta.org/consumer/news/20050531labupdate.htm

 

[Gemmal]

Bingo, that''s exactly what it looks like. Except it does not intersect at all. The lines only go in one direction and cover the whole surface. It is not in bunches. It looks like I got a paint brush and swooped across the enitre surface evenly. Could that be rutile silk?

 

[Gemmal]

I forgot to say that my alex is not a cats eye but a faceted one. Should the silk be intersecting?

 

[Richard M.]

Date: 6/25/2006 6:02:05 PM
Author: Gemmal
I forgot to say that my alex is not a cats eye but a faceted one. Should the silk be intersecting?

Facet-grade stone and cat''s-eye material come from the same deposits. Because of that silk is a common inclusion in faceted chrysoberyl. I think I mentioned above that it runs in one direction and almost never intersects to create star stones; they exist but are rare.

Richard M.

 

[Gemmal]

So then the silk would not intersect in both the faceted and catseye alexandrites? Thank you so very very much for all your excellent opinions. I value them very much.