Hallmark "Arch De Triumphe"

by Cheryl
(Maine, USA)

My very old bracelet, ornate gold, has 14 Australian opals and 14 Diamonds, and a hallmark on the clasp. Appears to be the Arch' De Triumphe. I can not find that hallmark in Library. The age of bracelet is unknown.

I have had this jewel for 30 years and previous to that my mother-in-law owned it until she died (probably 25 years). She purchased it second hand from a Jewish lady of her aquaintance. Any ideas? Information?