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Gm vs. dwt


#1

The “Real-World Pricing” thread:

I notice a lot of you use grams when dealing with gold and silver
pricing.

I can understand (though not agree with) this practice by gold
buyers and pawn shops to confuse the customer, but why make your
lives complicated by not using Troy weight in your dealings with
precious metals?

Paf Dvorak


#2
I can understand (though not agree with) this practice by gold
buyers and pawn shops to confuse the customer, but why make your
lives complicated by not using Troy weight in your dealings with
precious metals? 

I simply prefer the more logical metric system overall. For one
thing, measurements like length and width and thickness of stock make
much more sense in metric.Compare that to width and length in
fractions of an inch (or decimal, which is better) and then thickness
with standard gauges, which relate to pretty much nothing else on the
planet. With metric, it’s easy, for example, to calculate what a
piece will weigh when I know the millimeter dimensions, simply
multiply the specific gravity (density) by cubic millimeters and get
weight in milligrams. Don’t need a calculator (or pencil/paper) to
convert from milligrams to grams or similar decimal divisions. With
Pennyweight or other troy weights, which are not logically connected
to anything other than tradition, there are extra steps. For me, I
only use troy weight when actually ordering the metal.

It’s easy enough to translate from the metric to troy when I need to
for pricing or the like. But for simply working with it, I’ll stay
with metric.

Peter


#3

Hi Paf,

Errr. most people have gone over to metric long since, at least in
my experience.

I can still do the dwt conversions if I have to, but other than
keeping 31.1 in my head for troy oz, I haven’t used pennyweights in
years.

Nothing to do with confusing the customer, but a very great deal to
do with not confusing me.

Puzzled regards,
Brian


#4

I am with Alberic on this one when I hear grams I can calculate troy
oz and also carat weights in my head maybe because it is how my math
part of my brain works but I find it easier to associate grams

Teri


#5
use grams when dealing with gold and silver pricing. 

At least according to this site, the gram is the most popular unit
for weighing gold: http://www.ganoksin.com/gnkurl/ep81ol

As for confusion, I think the average customer is more confused by
the difference between troy and avoirdupois weight.

Al Balmer


#6
Nothing to do with confusing the customer... 

So when a customer wants you to buy his scrap gold and says, “Hey
friend, I know gold sells for $X per ounce, and my piece weighs
exactly one ounce…” I get how you explain the alloying, but how do
you explain that the price in the newspaper is about a 31.1 gram
"ounce" rather than a 28 gm ounce?

As to being confused, you’re converting Troy to Avoirdupois, doing
maths, then converting some more to come up with an answer I get by
simply dividing. What could go wrong?


#7

I work mainly in sterling silver and buy it in troy ounces. Pricing
it in grams makes a lot of sense to me as all that I have to
remember is 31.1 grams /ounce (I usually round to 31). You can see
this work in the pricing spreadsheet that I posted recently. Gold is
another story, but I rarely work in it. My two cents. Rob

Rob Meixner


#8

Israel has always been totally metric. Even precious metals are sold
by the kilo/gram. It’s certainly much easier. Hasn’t all of Europe
always been metric?

Janet in Jerusalem


#9

Not sure it matters what system you use if it works for you. I think
convention is silver is sold in in ozt and gold in dwts. or ozt in
bullion. The conversion is easy enough. After purchase, I convert
everything to grams before I put in inventory so I can easily
calculate what inventory I use in a piece and COGS. and can use the
same system for gold or silver. Just my preference. You could do it
just as easily in any other system. I can’t imagine trying to
fabricate using the english system. I"m comfortable with the english
system. worked as a machinist for years, just don’t think 64ths work
for me anymore :slight_smile: There is great utility in the metric system. If we
had 64 fingers or toes the English system might be more
intuitive… and we take the english system to base 10 to make it
useful for precision work anyway. thousands of an inch. Base 10…
we are programmed for it

Don’t ever market how much gold is in an object. then you are just
selling gold :slight_smile:


#10

Hi Paf,

I rarely buy scrap gold, so it doesn’t come up. (and when it does, I
do it by grams. Explaining about the 31.1 gm/ozt conversion.)

I do cast with student’s gold, so it does enter into that. The way I
explain it is to say that there is a very good reason why I normally
use metric measurements: I don’t have to keep track of whether it’s
a Troy ounce, or an Apothecary’s ounce, or an a Avoirdupois Ounce.
(All of which are different.) And when mixing a recipe, I never have
to ask “Is that a liquid gram?” (Liquid ounce, or weight?)

Grams are grams. So unless they come in with some sort of troy
weight already in their heads, we just measure in grams and stay
there. I do explain that precious metals are still normally sold by
troy ounces, and that there are 20 pennyweights in a troy ounce, but
the only thing they really need to know about it is that there are
31.1 grams in a troy ounce. Convert to metric as the first step, and
away you go. I can also weigh in grams (roughly) with a graduated
flask or syringe if I have to. (1CC of H20=1gm of weight. That’s
saved my bacon more than once at workshops.)

We don’t ever convert into avoirdupois. Can’t imagine why you’d want
to.

Regards,
Brian


#11

Hi Brent,

Doing a lot of machinist work these days, all the Knew Concepts
stuff is based in English, but in thousandths of an inch. (decimal
inches) rather than fractions.

I don’t care which system, really, just don’t ask me to figure out
whether or not 33/64 is bigger than 7/16. No fractions! (and don’t
ask me to convert. Just pick a system and stick with it.)

Actually, I sat down and thought about it for a second, in my
’medieval metalsmith’ mindset.

The original english system of 12ths does make sense, for a
population that were pretty much illiterate, and didn’t understand
math either.

Running in 12ths is the lowest denominator that lets you handle
quarters and thirds easily, while still handling halves. Which was
about as much as most people needed to do. For hundreds of years.

Switching to 24ths gives you the same ease of thirds or quarters,
while doubling the resolution. Suddenly begin to notice that karats
run in 24ths? It made the math easy. Same origin for sterling.
(.925) I don’t remember what the math was, but it had something to
do with some sort of easily derived set of weight proportions that
got you to.925.)

For serious work: decimal all the way.

Regards,
Brian


#12

Hi Janet:

Israel has always been totally metric. Even precious metals are
sold by the kilo/gram. It's certainly much easier. Hasn't all of
Europe always been metric? 

Define “always”…

Or, as I’m howling with laughter, No, it hasn’t. (and anybody who
can quote Pliny off the top of her head ought to have known that…
.) How do you think the US got stuck with some of the oddball
measurements we’re using? We couldn’t have thought this crap up on
our own. We inherited it from the Brits, and to a lesser extent the
French and Germans. We just couldn’t manage to get rid of it in
time, and now we’re sort of stuck with it. Sort of like QWERTY
keyboards. Just about the worst possible keyboard layout, but
everybody knows it, so it sticks.

Regards,
Brian.


#13
As for confusion, I think the average customer is more confused by
the difference between troy and avoirdupois weight. 

For sure.

Paf Dvorak


#14
I am with Alberic on this one when I hear grams I can calculate
troy oz and also carat weights in my head maybe because it is how
my math part of my brain works but I find it easier to associate
grams 

I still use pennyweights (dwts). Dividing by 20 seems easier to me
than dividing by 31.1.

Andy Cooperman, Metalsmith


#15

Hi Brent,

Following along on my ‘mental arithmetic for the Medieval Mind’ I
just remembered something: Arabic numerals.

We (now) are intensely focused on base 10. They weren’t. Up until
about 1000, the best they had was Roman numerals, which are nearly
useless for anything more complex than basic addition and
subtraction. Roman numerals are more-or-less base 10, they don’t
have any of the handy base 10 shortcuts that Arabic numerals do, so
there’s no real reason to focus on base 10 if you’re working in
Roman numerals. Arabic numerals didn’t really take over until the
1400’s. Held on in some respects (like clocks) until the 1800’s.

So if you can’t read, you don’t have a decent number system to write
with even if you could write, fractional systems like the English
12ths make sense: You can do them in your head, so long as you don’t
focus on getting them out into a decimal system. Stay in fractions
and you’llbe just fine. Kitchen math.

Remember, prior to about 1500 most metalworkers were mostly
illiterate too. There were some spectacular exceptions, but most of
the trade weren’t. So even for us, we have a lot of traditional
formulas and math that can be done without writing anything down.

Regards,
Brian.


#16
At least according to this site, the gram is the most popular unit
for weighing gold: http://www.ganoksin.com/gnkurl/ep81ol 

maybe, but I noticed that this site (who’s owner appears to be
annonymous) also thinks gold purity is measured in carats, not
karats. Spelling counts, right? :slight_smile:

I would agree, though, that overall, metric is used more worldwide
than troy, once one is away from the financial and bullion or gold
coin markets, especially at the consumer level with jewelry.

Peter


#17
As to being confused, you're converting Troy to Avoirdupois 

The only time I can imagine you’d be converting to or using
avoirdupois would be if you’re stuck using a kitchen scale or the
like that doesn’t know about troy weight. It’s troy or metric. Does
anyone ever need avoidupois weights of metals?

Peter


#18
also thinks gold purity is measured in carats, not karats. Spelling
counts, right?:-) 

In North Anerica, maybe. From Tom Herbst’s new book on faceting: "…
12 carat is 50%, and so on. To help minimize confusion, North
American jewelers use the term karat (abbreviated to kt) for gold."
Wikipedia says “Karat is a variant of carat.” Both Tom and Wikipedia
point out that millesimal fineness is used in Europe.

Al Balmer


#19

and on a final note the mathematician in the family looked up and
said what does it matter as long as you get the correct result? Do
what is easiest for you to remember. LOL

Teri


#20
also thinks gold purity is measured in carats, not karats. Spelling
counts, right? 

Yes, but that’s not the case in the UK. We use ‘carat’ for both gold
and It’s an English site (as opposed to American English)
which you can tell from the way other words are spelled e. g.
‘jewellery’.