I was looking at some corundum under the darkfield loupe. I was thinking maybe I could see curved straie for the synthetics and something else for the natural. However what I am seeing is some lines that are parallel to the facets, which look like maybe facets that aren't as polished? Should I be able to see growth straie in 10x darkfield?
Doesn't the direction in which one looks at the stone potentially alter the appearance of growth bands? My understanding is that curved bands can potentially look straight if you view the lines parallel to crystal face in which they were formed.
Joined: Wed Jun 15, 2011 8:29 am Posts: 123 Location: London
Of course the direction matters when looking at the stone, that's why you have to check it from all sides. Only along one plane growth lines will clearly be visible, it's like looking for circular shape with a glass- you have to look right down it. Curved lines won't look straight from different direction because they are layers, like in a tree, they may appear straightish if stone is coming from large boule (talking about synthetics). In natural stones the growth lines will follow hexagonal shape or any part of it ( like straight line, two lines meeting at an angle etc.) Hard to tell without good pictures what we are talking about here...
There can also be "polishing" lines on the facets as you mention. They are at the surface and is best viewed by reflected light coming in sideways. It can be seen through the stone sometimes but should be pretty easily distinguishable from growth phenomena.
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