On Sun, 10 May 2009 01:54:32 -0700, in rec.crafts.jewelry
" wrote:

Hi,
A few months ago I set a lab-grown sapphire into a sterling silver
Comfort-Fit ring for my son's girlfriend, who gave it to her mother
for Christmas. Her mother wore it daily but it now has a small chip in
the side. (You can't really notice it from the top) There's also a
small scratch on the metal, so I think she might have hit it on
something.
Isn't lab-grown a 9 like natural? Should this have chipped? Is there
anything that can be done beside reset it with a new stone?
Any and all info and suggestions gratefully accepted.
Regards,
Judith

Judith, if the lab grown stone is a true synthetic, then it, like natural
sapphire, is aluminum oxide. That is indeed a 9 on the mohs hardness scale.
Note that the term "lab grown" does not always mean the same thing as the term
synthetic, which would require the stone, if also labeled with the term
sapphire, to indeed be a true synthetic sapphire. Lab grown only means grown in
a lab. It's not a legally defined term, while "synthetic" as applied to gems,
is defined in FTC rules. However, most of the time, "lab grown" sapphires
purchased from major suppliers are indeed synthetic sapphires. Some ebay
sellers or the like, though, might play fast and loose with the terms.

As to the chip, there is a common misconception between hardness and toughness.
Hardness refers to the ease with which one material can scratch another.
Sapphire can scratch glass, but not the other way around, for example, so
sapphire is harder. But hard doesn't mean a material cannot be broken or
fractured. As an example, the sharp edge of a piece of glass can easy scratch a
piece of plastic. The glass is harder. Not drop both on a hard floor. The
plastic does not break, while the glass, more brittle and less tough, does
break. Another example: Diamond setters, using steel tools to set diamonds,
occasionally accidentally chip diamonds. The diamonds are much harder than the
steel, but the diamonds are not always as tough. Hit a diamond with a piece of
steel, the diamond breaks, while the steel gets scratched in the process.

Sapphire, while very hard as gems go, is somewhat brittle. Hit it wrong on an
edge, and you can chip it. The kitchen ceramic sink, or the bathtub, for
example, or a bit of a brick wall. Who knows. Lots of surfaces one might hit
the stone on are hard and rigid enough to transmit a sufficient shock to the
stone to chip it, even if those same materials are not hard enough to scratch
the sapphire.

If the chip is not severe, live with it. This is something that will happen
over time to most gems, even diamonds if worn long enough, especially if the
wearer also has diamond jewelry that might also bump the stone. You can replace
the stone, of course, but what happens when the owner again hits it by accident,
probably not even realizing she's done it, and it chips again. Wait until it
looks really worn, and THEN replace it. Or, if the replacement costs more than
maybe ten or fifteen dollars, you can have the chip recut and polished. Any
good lapidary that does facetting can do this. The stone gets another facet,
and then is slightly less symmetrical, but the chip is not then an obvious flaw.
Costs range, depending on who does the recutting and how much it needs, from
about ten dollars on up. A full recut of the entire stone restores all the
symmetry, but then the stone is smaller, and usually costs somewhere in the 30
to 50 dollar range, depending on the cutter, the complexity and size of the
stone, etc.

Hope that helps.

Peter