Refraction of Synthetics

What is the RI of synthetic stones ( not CZ ) ?

Hi if it is a synthetic corundum, emerald, ruby or any other known gemstone, it has the same properties/composition as a natural gem subsequently it would have the same RI

thanks

I’m looking for anyone who may be able to help in finding me a buyer for my unique stone Willing to pay commission if right buyer found . I am in United Kingdom