The Christmas tree in my dining room has silver crosses and crystal ornaments that I have collected for years. I actually keep the crosses in tarnish proof fabric bags, separate from the boxes they came in, so I can’t tell you the particulars about this design. I have collected the crosses since 1976 (I stopped in 2006) and love to see them out at Christmas!
Lovely piece- the pattern on your cross is called a "triquetra". The three interlocking "ribbons" were adopted from Roman art and possibly even earlier drawings by Christians to symbolize the Trinity and often appears on Celtic crosses and in Celtic manuscripts. It is sometimes looped by a circle as well which speaks of the eternal nature of the Father, Son and Holy Spirit.