Doublets were apparently often used in jewelry at the time of the
early period of the store where I work. (established in 1930, bought
out a store from the 1850’s) These stones are the typical fused
garnet top to glass pavilion. It is frankly amaxing how good some
look face up. There is not an easy “eyeball” recognition of the
garnet crown. I suspect many were sold, even some to unsupecting
buyers. Since I was not alive then, this is only speculation as to
the honesty in selling. Certainly, as simulated gems, some of the
garnet doublets do justice to the “look” of the natural gemstone.
Others, well, the glass color is just too blatant.