A 155 carat (synthetic) diamond with 92 mm diameter

Diamonds are neither rare nor extremely valuable, big ones are usually better off being cut up.

Synthetic diamonds are harder than natural ones:

https://en.wikipedia.org/wiki/Synthetic_diamond#Hardness

"In May 2015, a record was set for an HPHT colorless diamond at 10.02 carats. The faceted jewel was cut from a 32.2-carat stone that was grown within 300 hours."

 

I am assuming this will be used for industrial purposes, like most synthetic diamonds?

 

Epic engagement ring.