It means that its only gold plated
The jewelers mark means it has just been marked by a certain person. Think of it this way a brand you brand cows with is a mark of a farmer so he knows what cows are his. That is what a jeweler does.
It probably indicates gold plate.
Jewelers' Circular Keystone
SETA Corporation ended in 2009.
Atsuko Seta was born in 1955.
HDS is the maker's mark for Helzberg Jewelers.
Seta in biology is bristel or stiff hair.
SETA Corporation was created on 1985-10-01.
Seta Hagopian was born on 1950-07-28.
Seta Tuilevuka was born on 1981-10-27.
Détour De Seta was created in 2004.