Authentic early Roberto Coin necklace with his stamp on the clasp which is a star 1226 VI, plus Italy and 18K, The necklace does not have the hidden ruby which my research shows was only used since 1996 and Roberto Coin was established in 1977. I believe the necklace is from his early years. The true facet web site addresses the ruby identification as shown in this excerpt.
Many-but-not all-Roberto Coin pieces have a small ruby set on its inside or under side. The brand began production in 1977 but did not introduce their ruby signature until 1996. Therefore, alleged Roberto Coin vintage styles pre-dating 1996 that include a ruby signature are forgeries.It is a beautiful delicate necklace and would make a nice gift. I did not see any visible flaws, just some scratches on clasp under 10x loupe and the top half of the 8 (18k mark) is worn. Gem: 7 diamonds (see photo, tested under UV and the diamonds fluoresce a light blue), exact carat weight is unknown and current Roberto Coin necklaces are.
35 carats, I cannot provide clarity info. The item "Authentic ROBERTO COIN 18K White Gold, 7 Station Diamond by Inch Necklace, BIN" is in sale since Wednesday, May 27, 2020.This item is in the category "Jewelry & Watches\Fine Jewelry\Fine Necklaces & Pendants\Diamond". The seller is "lca2130" and is located in Bay Shore, New York. This item can be shipped to United States, all countries in Europe, Canada, China, Japan, Australia.