In a 1994 Chipco catalog that I have it lists the following weights:
39mm Pro-Tech chips = 10 grams
44mm (oversize) chip = 13 grams
44mm octagonal chip = 13 grams
50mm x 89mm plaque = 38 grams
Unicorn 39mm chip = 8 grams

To muddy the water, the catalog refers to both the Pro-Tech chipcos and the Unicorn mold chips as "clay chips". I think this is just a catch-all term, as I DON'T think either chip is truly clay. I've heard the Pro-Tech Chipcos referred to as "ceramic" chips, but don't know if that means ceramic as in pottery, or just that the material may be "fired" or heated and/or compressed when the blanks are made.

The catalog also gives the option for a linen finish or a smooth finish, which we know about.