In the time of Revelation, they lacked the skills of precisely cutting the gemstones, especially the hard ones like diamond.
So gemstones were mostly just polished and used in their natural shapes (more-less).
The isotropic gemstones really need the cutting, and faceting to became beautiful, so they were not particularly valuable then.
Isotropic gems can look beautiful, when they are cut right. However, they are dead when the lights shines against their grain.
Whereas anisotropic look beautiful from any angle. The point of the article is that the gems stones chosen from all possible gemstones were the kind to look beautiful from all angles.
It’s only 1/16,000, or so, that the right gemstones could be chosen for this randomly.
Uh, no.
1) Diamonds, rubies and sapphires are all the basis of metaphors for extreme value in the bible
2) Diamonds, rubies and sapphires were all too hard to be cut, true, but emeralds were not.
3) While they were too hard to be cut, it was well known from nature that they COULD be cut, which would seem to make the notion of cut precious gems all the more miraculous.