This question comes up constantly and I finally got a definitive answer for my situation.
Context: I was choosing between two otherwise identical stones:
- VS2 G Excellent 1.10ct: $6,100
- SI1 G Excellent 1.10ct: $5,200
The $900 difference on the same size and cut.
What I did:
I paid $75 for a gemologist consultation at a local independent store. I brought the GIA reports for both.
The gemologist's finding on the SI1:
- Two small feathers (fractures) in opposite corners of the stone
- Not visible at 10x loupe
- Definitely not visible to the naked eye from any normal viewing angle
- "Eye-clean" in gemologist terminology
The VS2:
- One tiny pinpoint inclusion near the girdle
- Not visible at 10x without knowing exactly where to look
Practical conclusion:
Both were eye-clean. The VS2 was "cleaner" technically but you would never know looking at either ring normally.
I bought the SI1.
The important caveat:
Not all SI1 stones are eye-clean. The inclusion type and location matter enormously. A feather near the center-top is much more visible than one near the girdle. Always view the actual diamond (or high-res video) and check the clarity plot on the GIA report before buying.
The GIA report tells you WHERE the inclusions are. Learn to read it before you buy.
Paid for the gemologist consultation too. $75 well spent. She showed me exactly what 'eye-clean' means in practice.