What does 10k THL stamped inside a ring mean?

Well my ring has that but it is ingraved it it is probley the initioal of the person how made it it is a logo our something

10K stands for 10 carats or the clarity of the ring (the bigger number the higher value and price) and THL stands for pink topaz. I have a 10K THL ring too.

After a simple google search:

Thl® is a registered trademark used for Jewelry, Namely, Bracelets, Earrings, Pendants, and Rings, All of Which Are Made of Precious Metals and owned by Samuel Aaron, Inc.