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Possibly:
Graphene
Carbon nanotubes
Silicon carbide
Indium gallium arsenide, or InGaAs
If you google them with something like "silicon replacement" after the name your'll probably find lots of info...
Hmm, internets a good start?
Although they cannot be used for jewellery, there are plenty of practical applications for them.
They can be used as an alternative to silicon in computer chips or as ultra fine cutting instruments in medical procedures.
One advantage of making diamond film from tequila is that it is extremely cheap.
The scientists found that even the cheapest of tequila brands, averaging at $3 a bottle, are good enough to make diamonds.