"800" Stamp but Gold Metal

by Linda
(Teaneck, NJ)

I found some cufflinks which looked like gold and were stamped "800", so I assumed they were a low silver and were vermeil. When a jeweler worked on it, he said the underlying metal was yellow, not silver. What material could it have been; I find it hard to believe it was 19.2 kt gold. Any advise would be appreciated. Thanks.
Linda