Set of two antique split rings.

Smaller, plain:
not marked, tested as 9 carat gold, the gold is rosy in colour
approx 11.25 mm / 0.44 inches outer diameter.
approx 8.85 mm / 0.35 inches inner diameter.
weighs 0.42 grams. The split goes all the way around.

Larger, engraved:
not marked, tested as 12 carat gold, the gold is yellow in colour.
approx 15.1 mm / 0.60 inches outer diameter.
approx 12.3 mm / 0.48 inches inner diameter.
weighs 0.73 grams. The split is about 40% of the way around, one end tucks in tightly, the other has a gap to slot your fingernail into.