| Factor | Why It Matters | Recommended Action |
| Diamond quality (4Cs) | Largest single influence on the offer | Locate any existing grading report |
| Metal and hallmark | Gold and platinum are priced by weight and purity | Check the hallmark stamp |
| Condition | Chips, scratches and worn claws lower the price | Clean gently; avoid repairs |
| Documentation | Confirms quality and ownership | Gather certificate, receipt and valuation |
| Number of offers | Buyers price pieces differently | Obtain at least two written quotes |