What is a lab created synthetic ruby? In the late 1800s, ruby (the  mineral corundum) became the first gem to be created in a laboratory by  the French chemist Auguste Verneuil. In 1902, he announced the  development of his new flame-fusion process for synthesizing this  beautiful gem. In the 1920's, the early Art Deco years, synthetic ruby  and sapphire (both the mineral CORUNDUM), were extremely popular and  also the norm, for that timeline. The vast majority of rubies and sapphires  from that time period are synthetic gem stones. Synthetic corundum,  ruby and sapphire, have the IDENTICAL physical and chemical properties  as their natural counterparts. This means that they have the same  crystal structure, specific gravity, refractive index, hardness,  birefringence, and pleochroism as their natural counterparts. 

Since the  physical and chemical traits of natural and synthetic corundum are  identical, separating them can be a challenge. As gemologists, we rely  on INTERNAL characteristics seen under high magnification to separate  them. Inclusions seen with magnification will vary from natural to  synthetic and a gemologist will be familiar with these  characteristics.The number one internal trait that assists me with  separation are the growth lines seen under magnification. Natural rubies  will exhibit STRAIGHT (parallel) growth lines, while synthetic ruby will exhibit  curved growth lines, also called CURVED STRIAE, which appear much like  the rounded grooves of a vinyl l.p. record. 

parallel growth lines on natural ruby, note too how the growth lines meet at an angle, referred to as hexagonal growth lines:

curved striae on synthetic ruby:

Another typical finding,  synthetic rubies will glow brightly- intense neon pink, under exposure  to ultra violet light, a phenomenon known as Fluorescence. 

This is  tricky though, because there are natural rubies, that by virtue of the  chemicals present during their formation process, will also fluoresce.  Typically though, synthetic rubies tend to fluoresce much more intensely  than natural rubies.

Some of the physical traits associated with the ruby are  vitality, prosperity, courage, high energy, and leadership. Ruby is the  traditional birthstone for the month of July. I find the ruby to be a very dynamic gem that is full of energy, and highly aspirational.

Art Deco 10k white gold synthetic ruby ring, by White Wile & Warner- (Buffalo, New York), circa 1920. Available here: https://sundayandsunday.patternbyetsy.com/listing/505954727/vintage-early-art-deco-10k-white-gold