RANZI Diamonds fall into 3 categories:
– F Grade (IF purity level)
– G Grade (VS1 purity level)
– H Grade (SI1 purity level)

Diamonds above 0.31 ct. are graded as follows:

Cut:	excellent	(highest standard)
Polish:	excellent	(highest standard)
Symmetry:	excellent	(highest standard)
Fluorescence:	none	(highest standard)
Certification:	GIA	(highest standard)

Each diamond is assessed according to certain criteria, determining its price:

• Polish:
  is the quality of the surface finish, which is rated on a scale from: Excellent, Very Good, Good to Fair and Poor.
  
• Symmetry:
  refers to the proportion and symmetrical angularity of the upper and lower facets of a diamond relative to its girdle (the “join of a diamond measured at its perimeter, dividing the crown above from the pavilion below”). Symmetry ranges from: Excellent, Very Good, Good to Fair and Poor.
  
• Fluorescence:
  should be minimal – preferably absent. A high fluorescence level indicates the presence of gases during the formation of the stone. When subjected to special lighting, a diamond with a high fluorescence level will reflect a blue tone. Fluorescence levels are rated from: Absent, Faint and Medium to Strong and Very Strong.
  
• Certification:
  is equivalent to the ID of a diamond – a sine qua non for every item offered on the market. Certification has to be reliable and authoritative, bearing all the necessary information required for identification and traceability. This allows a stone to be properly categorized and correctly priced, enhancing its saleability.
  Established in 1931, the US-based GEMOLOGICAL INSTITUTE OF AMERICA (known as the GIA) is the world’s leading gemmological authority and its classification system introduced in 1953 has set the international standard for diamonds. Applying by far the strictest criteria, GIA-certified diamonds are much easier to sell than non-GIA certified stones.