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Choosing correct basket size for stone

I have a blue-violet high grade Tanzanite stone with the dimensions
of 12.5x8.5x7.5 and would like to know the best ring basket size to
use. Should I use a 12x10 basket or can I get away with an 11x9? I am
afraid that if I use the 12x10 that part of the basket may show
looking from top down. Also, it may make the customer’s option to
mount a set of diamonds on either side of the stone a problem if
there is too much distance due to the width of the stone being 8.5 as
opposed to an optimal 10. (in this example, I am talking about
ordering a stock ring mounting with the settings already cast in
place for mounting some small stones on each side of the gemstone) If
I go with an 11x9, this problem is eliminated, but do I have enough
play in an “11” prong to stretch to a 12.5 stone? Which of the two
options is the best way to go?

Shardan Jewelry

Tanzanite is a very brittle stone and in my opinion should not be
used in any ring. But if customer insist on having one, the setting
must be custom made to fit the stone exactly. This is the type of job
where there is no margin for error.

Good luck.
Leonid Surpin.

You can easily section the larger setting to work with your stone,
assuming its a 4-prong. If I understand the situation right, your
stone is narrower than the stock mounting. Slice thru the setting
parallel to the long axis, effectively narrowing the center head.

As was mentioned, Tanzanite is a brittle stone. If you try to shoe
horn it into a small setting you may find heartache.

But I hope you’re going to tell us the mounting is not 18K white.

Hi there! If the stone is expensive and important to you, you should
make the basket yourself to the proper dimensions. Otherwise, you
can buy 12 x 10 head, and cut it through the middle until the
dimensions meet 7.5. However, I’d caution you that the 12.5 might
not fit in the 12 head either, so you may even have to go to a
bigger basket and cut that down.

To cut down, I usually saw in half in one direction and then solder
(or laser if you’re lucky enough to have access) back together at
appropriate size. Then, cut in half the other direction and again
cut down to proper size and solder back together.

Don’t even bother with the 11 x 9 head - the prongs won’t stretch to
accomodate a 12.5 stone and you’ll just wind up frustrated and
wasting money. If the stone is oval, you MAY be able to buy a round
and stretch/compress it to an approximate shape.

Hope this helps and good luck, Holly Hawkins