| Factor | What to Check | Why It Matters |
| Grading report | Issued by an independent laboratory such as GIA, IGI or HRD | Confirms the stone’s measured characteristics |
| Natural or lab-grown | Written confirmation from the original seller or the grading report | Lab-grown stones usually sell for considerably less |
| Written offer | Price, weight, grade and the basis of the valuation | Makes offers comparable and open to questioning |
| Payment method | Cash, bank transfer or cheque, and when payment is made | Affects security and how quickly you are paid |
| Buyer transparency | Business registration and a physical premises | Helps confirm the buyer is established |