Here's another rarely seen or offered glass insulator made in France and (unlisted) embossing: Isorex (front) 233 FCSF [with "S" blot out] (reverse) FCSF = Ferrocaril Santa Fe, which is the Santa Fe Railroad. The SF railroad was established in the town by that name in 1888. It was a State Owned French Capital (financed) company, which explains why they used French insulators. Isorex stopped making insulators with that name in 1928, so we know this insulator is older than that. I believe I've seen this style listed in their 1906 catalog.

This Dark Teal Green insulator is in Near Mint shape with typical heavy wg rub marks, small bb peck and a small dome crack. Rarely comes up for sale with only a handful recovered several years ago and made in limited quantities. First email gets this rare railroad insulator for only $100 plus shipping.