how old is my ring? What would be its value?

by Dianne
(Kaitaia New Zealand)

I have a small 9 carat amethyst gold ring with the hallmark CL & S in the first stamp, the numbers 375 between two marks that look like an upside down V with an extra leg in the second stamp, 375 boldly stamped, then the last stamp could almost be a castle in a square stamp with the corners cut off.