General question: avoirdupois or troy?

When you are talking weights for silver or gold, buying or selling, do you use the avoirdupois system or troy? Do you have expectations?

1oz avoirdupois = 28.349g
1oz troy = 31.103g

16 avoirdupois oz to a pound
12 troy oz to a pound

1lb avoirdupois = 453.6g
1lb troy = 372.2g

Maybe it is simplest to just use grams?

 

Grammes for gold and platinum. Imperial ounces for silver. That's how it gets valued here.

 

I just use grams, the other weights, like penny weight, just confuse me!

 

I prefer grams and purity percentage for a scrap calculation as a starting point in valuing an item.

 

When buying raw materials it is always troy ounces and pennyweight.
http://www.hauserandmiller.com/fab/flatsheet.html

 

This is the source of my confusion. I've been told that precious metals are are in troy ounces. A gold coin I looked at had a certificate that stated 22k and had 2 weights in grams - one for the coin entire, and another, lesser, weight followed by 1/2 troy ounce pure gold.

I think grams are the way to go.

 

Precious metals had always been measured in troy,it really didn't change until certain people in the government wanted metric to be the standard for the country. The gold and silver buying/selling craze started and people had easy access to gram scales and not dwt. scales. If you worked with troy measurement for many years you probably wouldn't think about it.

 

There's excellent scientific and commercial reasons for using metric and a universal standard.