What I want to know is how would I find out why this works? I need to have an analysis of the angles etc so that this could be reproduced. Does anyone know anyone who does this sort of analysis that could direct me as to how to perform it or would do it themselves? I just need info to get me going.
Derek, I think Hanneman Gemological makes a simple device for this
purpose. It�s a protractor scale with a little shelf sticking out on
the bottom. You place the stone on the shelf table-down and read the
pavilion angles from the protractor. Since pavilion angles mainly
determine a stone�s optical performance this should give you the
you need. If you want to measure crown angles it
wouldn�t be too hard to support the stone upright in modeling clay or
something similar to get readings.
You could also use a goniometer to determine the angles. This
question was answered on the USFG list but �goniometer� was
misspelled which was confusing. The name is a fancy word for a
simple device that�s easier to use than describe. I�ve made my own
for the same purpose simply by cutting two straight fairly rigid
cardboard strips and fastening them together at one end with a carpet
tack so the pieces can be opened and closed like a scissors.
You simply slide the stone into the opening with one inside edge
against the table facet, the other against the facet to be measured,
then transfer the device to a protractor to read the angle. The
concept is simple but I find it helps to have an assistant to help
hold everything in correct position. Of course you could send your
stone to a gemological lab and pay quite a bit for the same