The reason for this is that most of the clasps used on vintage jewelry are also used on modern pieces.
Condition of the metal and other design techniques in the piece should be used in conjunction with a clasp to try and narrow down the date.
They were commonly used on necklaces and bracelets.
On a bracelet, a fold over clasp was often used in conjunction with a safety chain to help prevent loss of the bracelet if the clasp open while the piece was being worn.
If the metal is worn, the value of the piece is diminished, although clasps are one of the easiest findings to replace.
I’m republishing this old post in English, thanks to the outstanding help of my friend Mary Jo Barber, who kindly translated it for me.
4-piece jewelry suite consisting of a necklace, bracelet, earrings, and ring. Antique ball fob dating between the 1860's and 1880's. The buckle is two separate pieces which when connected measure 2 inches wide and 2.25 inches high. Item# JA-1500 Antique Chatelaine with six appendages - compact, lipstick case, notepad, pencil, coin compartment and needle case. Sky blue and Egyptian blue enamel in near perfect condition makes for a striking contrast against the gold overlay. Circa early 1900's this fine estate art nouveau period piece features baroque pearls set in sterling silver with gold highlights.
An elegant combination of ONYX stone and carved ABALONE shell on MOTHER-OF-PEARL. All pieces are in very good condition including clasps and fasteners. Lacy gold-gilt antique belt buckle with French blue glass stones in saw tooth bezel settings. Please click on image to your left for an enlarged view. A very few dings here and there appropriate to its age. Frame is possibly sterling, however, unmarked for silver content. A slight snowy appearance more marked in the photographs than in real life. Item# JA-0815-01 Lushly romantic filigree dangle earrings. Item# JA-505 The Art Nouveau movement may have faded at the dawn of the first World War but it left behind incredibly beautiful examples of its unique emotive beauty.
A fish hook clasp is made with a small hook which is inserted into a metal finding, often a pointed oval shape.The were made with a small box which had a tab which was inserted into it. Hook clasps were often used on multi strand necklaces from the 1950s and 1960s.They were made of a metal hook which either "grabs" a bead in a dangling strand, or hooks in to a metal chain.If you see shiny goldtone or silvertone barrel clasps or toggle clasps, the piece is likely to be a newer creation.As with other findings and stones which make up a vintage piece, condition of the clasp is important when you decide whether to purchase the jewelry item.