Help identifying maker of Art Deco Platinum and Diamond Charm Bracelet

This is an Art Deco platinum and diamond charm bracelet. Some of the charms also have rubies, emeralds and pearls.

The old style platinum bolt ring has a gold thumb piece and is stamped with four very rubbed model/design numbers that could be 2837.

The ring on the other side of the bracelet clasp is stamped with what could be an embossed "E" in an oval punch. Someone suggested it's the "Double C" for Cartier, but it seems too squared off? Hope it show up in the pics.

I have seen similar bolt rings on Cartier pieces, and the "key" charm is nearly identical to a marked Cartier charm on a similar charm bracelet on a high end antique jewellery site.

Can anyone identify the "E" mark and/or maker?

Thanks in advance for any suggestions or comments.