I bought this absolutely beautiful brutalist/modernist 9ct bracelet, and I adore it. However it was not cheap, and was bought as all 9ct gold. Upon receiving it I noticed the 375 hallmark had GS inscribed beside it. I hadn’t seen this before and the little information I could find online suggests this means Gold Shell. It is also marked 9ct A*D foreign, which stands for Andreas Daub. I can’t find much evidence they did solid gold pieces. Any help would be greatly appreciated on the GS mark as I will be returning it if it’s not solid 9ct gold!