If I have a sterling silver ring that weighs 4 dwt, how much would it weigh if I cast it in 14k yellow gold?

To answer that question we need to refer to the specific gravity of each of the materials in question. Specific gravity, simply put, is a measure of the density of a material as compared to the density of water. The easy to use formula and chart below are all that's necessary to find the answer to our question.

Weight of the original item multipied by (Specific gravity of desired material divided by Specific gravity of existing material) = weight of item in new material

Example: 4 dwt x {13.07 (specific gravity of 14 k yellow gold) / 10.40 (specific gravity of sterling silver)} = 4 x 1.25 = 5.02 dwt

The question that remains is, "Where can I find the specific gravity of various materials?" Below is a list of various materials and their individual specific gravity. Simply select the appropriate figures, plug them into the formula above, and you will be able to quickly convert weights from one material to another.

Aluminum 2.70
Brass 8.40
Copper 8.94
Gold 24K 19.36
10K Red 11.59
10K White 11.07
10K Yellow 11.57
10K Green 11.03
14K Red 13.26
14K White 12.61
14K Yellow 13.07
14K Green 14.20
18K Red 15.18
18K White 14.64
18K Yellow 15.58
18K Green 15.90
Platinum (pure) 21.45
Platinum Cobalt 20.80
Platinum Iridium 90/10 21.54
Silver (pure) 10.53
Sterling 10.40
Wax 1.00