Metal weight ratio

I am trying to calculate the exact weight ratio from silver model to
cast piece in 18K or Platinum. I realize that each casting often
varies a couple of percents, but do you have a common ratio figure
that I could work with. Today I did some calculations and came up
with the figure of 200% for silver to platinum. Meaning that if my
silver model weighs 5 grams, then my cast piece in Platinum will
weigh 10 grams. Is this a safe figure for calculating my cost on a
regular basis? And what about 18K white gold? Thank you and best
regards, Carl Blackburn

Hi Carl, All you need to do is divide your metal item by the specific
gravity of that metal, then multiply the results by the specific
gravity of the metal you are converting it to.


The following is a Sterling Silver converter:

Multiply Weight X       1.013 = fine silver
                                .995 = coin silver
                              1.112 = 10k Gold
                              1.256 = 14k yellow gold
                              1.497 = 18k yellow gold
                              1.704 = 22k yellow gold
                              1.866 = 24k yellow gold
                              2.062 = Platinum

Conversion charts can be found in the Hoover & Strong Catalog on

page 282.

Steve Burns