Weight is one dimension.
Carat is weight, not face-up size. A metric carat is 0.2 grams. Dimensions and proportions also affect how large a diamond appears.
Diamond guide
Knowledge before selection.
Understand the language of a diamond before you compare a specification, a report or a supplier quote.
Read the grading context.
Colour and clarity describe different characteristics. Compare the laboratory, report type and grading terminology alongside the stated grades.
Shape is not cut quality.
Round, oval and emerald describe shapes or cutting styles. Cut quality concerns how a diamond’s proportions and finish influence its appearance.
Source: GIA — Diamond Quality Factors; undated, reviewed 12 November 2026
Start with the origin category.
Ask whether a stone is natural or laboratory-grown, whether any treatments are disclosed, and what the laboratory actually examined. A visual inspection or seller’s description is not a substitute for appropriate laboratory identification.
Source: GIA — identifying laboratory-grown diamonds; reviewed 12 November 2026
What to ask before accepting a quote
Obtain the exact specification.
Record carat weight, measurements, shape, colour, clarity, cut information where applicable, fluorescence and disclosed treatments.
Check the report at its source.
Use the issuing laboratory’s own verification service. Matching report data is useful, but does not itself establish that the physical stone presented is the reported stone.
Compare the complete terms.
Check currency, taxes, shipping, insurance, return rights and any conditions before comparing totals.