Today I have a Givenchy necklace. It is obviously vintage - but I do not know the date. It has a flat, flexible chain and a press stud type clasp. It measures just under 16 inches. (Most necklace made today are bigger than this!). I like Givenchy jewellery! This ones is marked - see full details on my web site - www.gillianhorsup.com - ref: 2545 B122/50 Price £110. I usually have a few pieces by Givenchy in the shop.