My financee has a custom-made pink diamond ring in a platinum setting, and it cost much much more than 60k. Here is what we found:
If you're going to buy a diamond of that price and don't have something like a centurion, you'll want to pay for it with something other than a credit card (bank wire transfer, check, etc.). Even if you do have a card like that, at that level most jewelers or diamond traders will charge you a higher amount for using credit. Eating 3% of a price that high isn't exactly insignificant, so expect for that difference (or at least some of it) to be passed along to you.
EX 798, EQ 789, TU 784 American Express Platinum (NPSL) || Bank of America Privileges with Travel Rewards Visa Signature - $23,200 CL Barclays American Airlines Aviator Red World Elite Mastercard - $20,000 CL || Chase IHG Rewards World Mastercard - $25,000 CL Chase Sapphire Preferred Visa Signature - $12,700 CL || Chase United MileagePlus Club World Elite MasterCard - $26,500 CL Citibank Hilton Reserve Visa Signature - $20,000 CL || J.P. Morgan Ritz Carlton Visa Signature - $23,500 CL