When a jewelry store says a diamond is flawless, what grade is it actually?

Diamonds are typically categorized by clarity grades, starting with:

Flawless (FL): Diamonds with no internal or external inclusions.

Internally Flawless (IF): Diamonds that have no internal inclusions, but may have minor surface blemishes (visible only under 10x magnification), which do not affect the diamond's brilliance in any way.

Very, very slightly included (VVS1-VVS2): Contains very slight inclusions that are difficult even for professional gemologists to see under 10x magnification.

Very slightly included (VS1-VS2): Contains minor inclusions that are visible to professional gemologists under 10x magnification.

Slightly included (SI1-SI2): Contains inclusions that are easily observed under 10x magnification, or in some cases, visible to the naked eye.

Included (I1-I2-I3): Inclusions are clearly visible under 10x magnification or to the naked eye, and have a noticeable effect on the diamond's brilliance.

When we refer to "flawless" diamonds, we mean only the FL and IF grades. However, some jewelry stores may show customers a VVS1–2 grade certificate and claim it is a "flawless" diamond, which can be quite confusing! It is clearly stated in the certificate, after all. Therefore, whenever you receive a diamond certificate, make sure to understand each detail listed and don't just take the seller's word for it. :)