Diamond should arrive this week.
After this whole weeks of researching I reckon I know everything to know about diamonds, cut, clarity, colour etc....
For arguments sake an excellent cut, good colour/clartiy 1 carat round diamond with a GIA certificate would say cost:
Some Chadstone Store: $15,000
Some local cheap store: $10-12k
USA: $6-7k
Note this is just for the diamond itself not the ring.
In saying that you wanted know what your really doing before buying diamonds IMO