I've used 19 for re-tipping when I've needed to for various
reasons, but you have to be a good observer
I’ve used 20KWW for years on diamonds. I tried 19 and just didn’t
like it. I feel I have more control with the 20. With care you can
draw the solder slowly along the prong without it just gushing all
over the place. To me, the 19 tended not to flow as nicely, but
that’s just my experience.
The other thing is that tipping on top of a diamond is going to be
less dangerous than soldering under the stone. On top you can put the
heat exactly where you need it. Underneath you basically have just
one angle of approach. I suppose you ‘could’ try applying heat to the
opposite side of the prong, to draw it thru, but that strikes me as
asking for a frosted diamond. Girdles being more sensitive to
One trick I’ve seen but not had great success with is instead of
addressing the gappy prong, run the thinnest sawblade under the tight
prongs. The limiting factors here are 1) access 2) if your blade
thickness is not exactly what you need to compensate you are out of
luck 3) the stone will get lower.
If I were in the position of the OP, I’d pull the stone and adjust
the seats. Be aware that now the tip has been work hardened so it may
behave a little differently than the first time you set it. This is
one reason I like to start with overly long prongs… if you need to
pull the stone you have something to grab onto. Mucking it up with
tool marks is not pleasant.
Of course the best cure is to not need a cure. Typically I will cut
the seat in stages. After each cut trial fit the stone. Usually you
can see discrepancies before they are glaring and insurmountable.
Sometimes, no matter what you do the stone may rock as you cinch
down the prongs. A wavy girdle might be the culprit, or maybe the
table and girdle are not parallel. You need to examine the stone
before you set it. If its out of whack you need to indicate a single
point on the stone, so that as you individually cut the seats and
trial fit, the stone is always in the same relative position. For
example put a dot of Sharpie ink on one kite facet and always keep
that dot at 12 o’clock. Also indicate the mounting. For example
always keep the karat stamp on the left. What you’re shooting for
here is consistency of alignment between mounting and stone.
If you still have a rocky stone(hehe) and you just can’t get the
seats right, apply pressure always to the highest part of the stone
in little b ites. This way you can nestle that puppy into place. As
you see the stone level out (or even get worse) you can move to the
next highest side of the diamond.