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Estimating coin weight in 14KY


#1

I have a customer who wants a half-dollar sized/thickness 14ky charm
made.

I figured I could weigh a 1/2 dollar and convert the weight to 14ky,
but I have no clue how to do that.

Help?
Paf Dvorak


#2

A US Kennedy Half Dollar is approximately .085" thick with a
diameter of 1.2". A 14K Yellow circle that is .085" thick and has a
diameter of 1.25" (slightly larger) would weigh approximately 14.4
dwt.

Hope this helps.

Tom Morehead
Hauser and Miller


#3

Hi Paf,

The half dollar coin (1964 or earlier silver coin)would weigh 12.50
grams. The specific gravity of coin silver is 10.31 grams per cc.
14KY gold would have an average specific gravity of 13.07 grams per
cc. Divide the 13.07 grams per cc of 14KY by the 10.31 grams per cc
of the coin silver and you get 1.267. The 14KY would weigh 1.267
times heavier than the silver coin. The 14KY coin of the same size as
the half dollar silver coin would weigh 15.837 grams +/- minor
variations depending the 14KY alloy used.

Good luck & Best regards,

Jim Sivertsen
United Technical Dept.


#4
I figured I could weigh a 1/2 dollar and convert the weight to
14ky, but I have no clue how to do that. 

Easy, Paf, although of course it’s just an estimate. It’s a
proportion of the densities. The density of fine gold is listed as
19.3, the density of 14kt that we use for casting is 13.4. 19.3/13.4
is the amount of 14kt to make up the piece from fine gold - 1.44, If
your coin is 10dwt it will take 14.4dwt of 14kt. Of course if you
are wanting to make a 14kt thing into fine gold, it goes the other
way. You can use the same method to estimate silver items in
platinum (22/10.5), converting various golds, etc.


#5

Hello Pat,

do you mean you want to end up with a 22 mm by 1.78 mm thick disc of
14 kt yellow gold That’s about the size of a 1/4 oz american eagle
coin ( = 8.483 grams of 24 kt or 4.50 approx. of 14 kt.)

or do you want a 27mm x 2.25 mm coin (a half oz. coin size)? The
coins cost about $429.00 for the 1/4 oz. size and $859.00 for the 1/2
oz (16.966 grams of 24 kt. or approx 10.5 gm of 14 kt - so you can
figure it from the fine gold prices as of today’s mkt. and actually
doing the karat reduction division rather than approximating off the
top of one’s head like I’m estimating the 14 kt weights!)

Rio Grande, Hoover and Strong, Metalliferous and a number of other
vendors sell 14 kt. y die cut blanks in various gauges so a quick
look in the catalogues for a retail like price to use as a guide
depending on the amount of work, etc. you have to put into the charm
will help you come to a fair price for fabrication, etc. However if
you have sheet and disc cutters. why buy a blank? - unless there’s a
lot of engraving, design work, etc., that can’t be easily cast in
cuttlebone or delft clay or some other easy direct cast method? That
would allow you to reproduce fine detail (cuttlebone for instance)
without having to make a model, etc. just carve, remove the grain or
not (in the cuttlebone will have its unique texture unless you use a
brush to remove it and any excess could be cleaned after the casting
with some tripoli or bobbing compound before polishing or finishing
as the design dictates- the delft clay will remain fairly smooth)

One tip when dealing with custom jobs and face-to-face negotiations
with a customer - if you suspect have gotten into a project beyond
your skill level or don’t know exactly and immediately where to
source the materials and it’s a regular client, you could have them
return to approve the design you have rendered and for which you have
made a list of materials and reached a supplier, or worked out how
and when you’ll deliver what they want and at a price that accounts
for anything you have to order in and whether you consider the item a
"special order" or not. Sometimes findings and components you would
think would be easy to find, or that you would expect every vendor
would carry are not as easy to source as expected! Another thing to
consider when designing the size of the charm is whether or not the
customer had/has an ordinary pre-fabricated mount in mind to hold the
"coin-like" piece I think you are describing. make sure you check
that before having to modify something you hadn’t planned on when
laying out the job!. Good Luck,…rer


#6

A silver half-dollar 1963 and older, weighed 12.5 g, and was 90%
silver, 10% copper. Ignoring the difference in density between copper
and silver, gold the same size would be about 23 g. That’s about 0.74
ozt.

Al Balmer
Pine City, NY


#7

A silver half-dollar 1963 and older, weighed 12.5 g, and was 90%
silver, 10% copper. Ignoring the difference in density between copper
and silver, gold the same size would be about 23 g. That’s about 0.74
ozt.

Oops, you said 14K. Anyway, Jim Sivertsen got it right.

Al Balmer
Pine City, NY


#8
A US Kennedy Half Dollar is approximately.085" thick with a
diameter of 1.2". A 14K Yellow circle that is.085" thick and has a
diameter of 1.25" (slightly larger) would weigh approximately 14.4
dwt. 

Thanx Tom! Great answer! It’s the size and weight of that size I
needed, not the relative weight.

Paf Dvorak


#9

Pat, According to a chart I found on Google, coin silver has a
specific gravity of 10.31 and 14ky has an S. G. of 13.07. Divide the
bigger number by the smaller number and you get a difference of
1.267. So 14ky is 1.267 times heavier than coin silver. Weigh the
coin and multiply by 1.267 and there’s your answer. If you are going
to cast the piece, add another 30 percent or so for the button.

Jerry from Kodiak (currently in Bangkok where it’s 104 deg. F.) Whew!