3. Diffusion Star Sapphires-
Use
of chemicals/heating on the surface of the stone to change the color or add a
star to a stone that normally doesn't contain
one
4. Linde Stars(Artificial/Lab Created
Star Sapphires)-
Stone is synthetic, star and color synthetic as
well
5. Fracture Filled-
Oil, Glass,
Resin or Epoxy fills cracks or fractures, usually unable to detect without
optical instrumentation
At Simply Sapphires, the great
majority of our stones are Natural Mined Untreated Stars, although we do carry
a small few of the others, check the individual stone listing for
details.
How Can You As a consumer tell the difference? You
Can't, It really takes a well equipped laboratory, to detect the intricate
processes performed. My experience has been jewelers and most gemologists
don't have the proper equiptment to give you anything more than an educated
guess. so if you have any question, send it to the AGTA, GIA or EGL gem lab,
or a well recognized established lab.
Tips on What to Look For On A
Star Sapphire
1. First thing to look at is the
bottom, if there is an "L" stamped in the stone, it's a Linde Star and
synthetic... Linde stars were manufactured en masse by the Linde division of
Union Carbide since about the early 1950’s.
2. Next look for
imperfections within the stone, or an unevenness on the bottom, or stripes or
bands of color that shows through the top, most naturals have one or more of
these natural imperfections.
3. Take a good look at
the star itself, using a flashlight, most natural stars do not have a
"perfect" star, whereas the natural will likely have one or more of the six
legs uneven in length, or maybe not
perfectly straight... the star must travel around following the light source,
if the star is stationary it is definitely synthetic. The most common
synthetics jump out as way are too perfect looking and the star might only
move one direction if at all.
4. Color is extremely important, top quality
stars have top quality color, pretty simple.
5. The legs of the star should be complete and sharp, with
no missing or broken legs, and each ray should extend to the girdle of the
stone.
6. The more transparent or translucent the stone the better. Tricky
though, because sometimes with too much transparency the star is not
evident.
How rare are these gems? For every 100 faceted
corundum (ruby and sapphire) mined, approximately three stars are discovered.
One will have good color and a bad star. One will have a great star and bad
color. Only one out of a hundred will have a good star and good
color.
Fine stars are pretty rare. Until the 1960s,
these stones always sold for more than the faceted ruby. For example, in the
late 19th century, three carat star rubies went for $3000 per
carat.
