Variations in the size stones a piece is advertised as fitting and
what it actually fits can be quite different. 0.1mm is pretty close,
but it can be a huge difference percentage-wise at that size. Without
seeing the mounting and stones together personally, I don't know how
your 1.5's will actually fit; they might work fine or they may be too
small or too big. Small CZs have a tendency to have thick girdles
which can add to the difficulty of setting them, especially if the
mounting is a tiny bit on the small side.
The mounting you posted is not really bead set, it's what is often
referred to as "pin set". The difference is that in bead setting,
the stones are set down into holes in the piece so that the tables
are somewhere around flush with the surface, the beads are formed by
cutting away everything except the beads and it generally has a
bright cut sidewall. Pin setting on the other hand is characterized
by the stones essentially setting on top of the piece, with raised
'pins' or 'prongs' cast in place and are set by pushing the pins over
the girdles and crowns. Pins are generally pretty short, so they can
be difficult to deal with when setting stones that are too large or
that have thick girdles. There's just not much room for error.
When I'm pin setting, I'll go over the holes with an automatic
center punch set at a fairly low impact strength before doing any
seat cutting, with the objective of opening the holes up a little and
pushing the pins apart a little. It tilts the pins out so there's a
little more metal to work with when pushing them back over the
stones. You can also use a broken bur that has been ground to a blunt
point to wallow the holes out and bend the pins out a bit. However
you decide to do it, make sure you bend the pins out a little from
where they were cast.
Then I prep the seats with a cone bur the diameter of the hole
inside of the pins (barely touching or just missing the inside of the
pins), cut the seats with a 90 degree setting bur the same size or
slightly smaller than the stones, touch them up or under-cut them a
little with a hart bur if necessary, set all of the stones in place
with beeswax and then gently and barely close the pins, a pair at a
time, back to where they were before bending them out.
I look for any stones out of level or at an incorrect depth and if I
see any, pull a pair of pins back, lift the offending stone out and
fix the seat as necessary. Once I get them all level and straight, I
go over the whole strip end to end a few times to tighten them all
up, watching all the time for stones trying to sneak out of level. I
use a special pair of pliers I modified specifically for pin setting
by grooving the tips, or a grooved prong pusher to ease the pins down
on the stones. I'll even sometimes use a pair of ring bending pliers
to squeeze the beads straight down, but go easy if you try this
little cheat. It's really easy to break stones or flatten the pins
out to nothing.
Another method of pin setting is to set one stone, cut the seat for
the next one, set a stone in the seat, close the pair of pins between
the two stones, cut the next seat, set it, close the next pair and so
on for each stone. In that case, I start at the top and work my way
down one side and then the other. You have to be watchful using this
method that the spacing of the stones stays right so you don't get in
trouble at the bottom of the row. It can be tricky with stones that
are a little on the large size.
If you get a seat too deep for one particular stone, try swapping
out stones 'til you find one that's extra deep. If a seat's not quite
deep enough, try swapping stones out looking for one that's a little
shallower than the rest. I like to sort of reserve the
deepest/largest and/or shallowest/smallest stones for the very last
seats. That gives you a little fudge-factor if you get carried away
with cutting a seat or find that because of the pin spacing, one of
the seats at the end of the row is going to be a little too small no
matter how careful you are. You'll get an idea of how they are
trending size-wise and what you should save for last as you go. It's
like chess; always be looking four or five stones ahead of where
you're cutting and setting.
Here's another picture of the shank with stones already set that
makes it look like there's no need to cut seats which is why I
didn't try to cut seats:
The bane of CAD/CAM. You know, they can actually make a diamond
hover over a ring with no setting at all using CAD? I've seen it!
Seriously, a real piece of jewelry seldom looks like a computer
image. Don't try to figure out how something is set by looking at CAD
images of the finished piece. They're really only useful for selling
and winning contests. A lot of CAD artists that really know their
stuff will actually often do a separate image of the finished piece
just for showing the retail customer, they can be that different from
one that's actually usable by a goldsmith.
Hope this helps.