Better yet, print it on the back of your GPAA card... I'm OK with the gram and ounce thing, its the grain and pennyweight thing that I can't
remember.

The Gold Lady in Kingman had the conversions on her business card. I thought that was handy.

Something like these, or am I missing a few or something else entirely?

Formula for determining the amount of gold in a specimen of quartz:

* WG = Weight of gold in specimen
WW = Weight of specimen in water
WA = Weight of specimen in air

Amount of Gold in:

24 k = 100% gold
22 k = 91.7% gold
18 k = 75% gold
14 k = 58.3% gold
12 k = 50% gold
10 k = 41.7% gold

Weight Conversion Table
24 grain = 1 pennyweight (dwt)
20dwt. = 1 troy ounce (oz)
12 oz. = 1 pound (lb.)
1 grain = .0648 grams
1.5552 grams = 1 dwt.
31.104 grams = 1 troy ounce

Thanks Paul, the last was what I was thinking about, but the other two are handy as well.

Not in the world of Troy Matt. Troy ounces and pounds are different things.

A pre 1982 penny made of Copper or a post 1982 penny made of Zinc?

This is were it gets hard, how do you identify counterfeit from real, gold coins or fakes, real silver rounds or sterling copies?

If this is what you are interested in send me a PM and I will teach you the tricks of identifying counterfeit materials, this can be quite the task these days even for professional dealers. There are a lot of gold bars being sold with tungsten plugs inside of them, and they cannot be identified until the are melted. Jewelry is even more difficult to detect if it is real or not.

That 14k stamp on the bottom of the ring has about as much value as a counterfeit $10,000 bill, zilch.

With all of these knowing your weights is critical, and a small very accurate scale you calibrate yourself is important, but so is a rare earth magnet you use as a standard.