When you buy a house, it comes with a deed that details the measurements of your property. Your car has a title and registration. You also need documentation for your diamond engagement ring.

That documentation is diamond certification, properly known as a diamond grading report. And no diamond documentation is respected more than a Gemological Institute of America certificate.

GIA certification isn’t an appraisal. It’s the scientific blueprint of a diamond’s exact quality characteristics. GIA certification is your assurance that your diamond is a natural diamond and hasn’t had any treatment you don’t know about to enhance its color or clarity. GIA certification gives you the independent verification you need to feel confident in your diamond purchase.

GIA is a research and educational institute and doesn’t sell diamonds or represent the diamond sellers. Instead, GIA acts as an independent, impartial entity for assessing and delivering comprehensive gem quality information.

There is a good reason why the GIA Diamond Grading Report has become the benchmark for diamond certification around the world.

The GIA literally invented the diamond grading scale and those famous 4Cs of diamond quality. Since GIA is non-profit, consumers know they will receive the world’s most impartial and accurate analysis of their diamonds. GIA operates nine gemological laboratories around the world.

In addition to certifying diamonds and gems, GIA is the world’s leading gemological education institution. Over the course of its 85-plus years, the Institute has educated more than 365,000 professionals worldwide. All of the other gemological laboratories use the grading system developed by GIA and have gemologists and graders who have been educated by the GIA.

GIA certification gives you independent unbiased scientific verification of the quality of the diamond you are purchasing. The quality differences in diamonds can be so subtle, even a jeweler can’t recognize them without lab verification. Insist that any diamond you buy come with GIA certification.

Your GIA diamond certificate will be in good company. GIA laboratories have graded some of the world’s most famous diamonds: the 45.52-carat Hope Diamond, the 273.85-carat De Beers Centenary Diamond, and the 69.42-carat Taylor-Burton Diamond.

One of the most important features of the GIA certificate is one of the most basic: the report number. GIA has an online service called Report Check that’s like block chain for diamond certificates. You can put in the number on your certificate and see the data from your report online direct from the GIA so you can confirm that the report hasn’t been altered or misrepresented.

The GIA certificate number is often engraved on the girdle of the diamond so that you can confirm that your diamond matches the grading report. You can read the GIA report number with a diamond loupe or a gemological microscope.

GIA offers different diamond certification services: the GIA Diamond Grading Report, GIA Diamond Dossier, GIA Diamond Focus Report and GIA Colored Stone Identification Report. To insure accuracy and consistency, GIA grades only unmounted diamonds. Pricing depends on the size of the diamond and the type of report.

GIA certification also confirms whether your diamond is natural or lab grown and whether of not it has been treated.

The standard GIA Diamond Grading Report is a full printed assessment of the quality of natural D-to-Z color diamonds of 0.15 carats or more based on the 4Cs of diamond grading: color, cut, clarity and carat weight. This GIA certification includes a plotting diagram of the diamond’s unique clarity characteristics like inclusions and blemishes. The inscription of the report number on the girdle of the diamond requires a small additional fee. Full certification of a one-carat diamond is $105 plus $15 for inscribing the report number on the girdle.

For diamonds that weigh 1.99 carats or less, you can opt for the printed GIA Diamond Dossier instead of a full report. The Dossier includes the same information as the Grading Report, except for the plotting diagram. A Diamond Dossier for a one-carat diamond is $85. A laser inscription of the diamond’s GIA Report number is included at no additional charge.

The most affordable GIA certification is digital only: the GIA Diamond eReport. This online report is available for natural, D-to-Z color diamonds from 0.15 to 2.99 carats and is available via Report Check, GIA’s secure web-based report database. Instead of a plot diagram, the eReport has an image of the diamond with notes about inclusion types and locations. An eReport for a one-carat diamond is $80, plus $15 for report number inscription.

The GIA Diamond Focus Report is a new digital report for natural, loose, D-to-Z color, round brilliant-cut diamonds weighing between 0.15 and 0.29 carats. This digital report includes carat weight; color, clarity and cut grades, polish and symmetry grade and a fluorescence description. Laser inscription of the GIA report number is included. Although GIA does not issue a printed Diamond Focus report, a summary of the results can be printed from Report Check. A diamond focus report is $32 for a 0.39-carat diamond.

GIA certification is also available for synthetic diamonds with fewer quality grade categories. The synthetic diamond grading reports include a laser inscription of “laboratory grown” on the girdle.

GIA certification is essential for fancy colored diamonds, which can sell for millions of dollars. Unlike colorless diamonds, which are graded for their absence of color, fancy-color diamonds are graded for the intensity and hue of their color. Shades that are deep and distinct are rated higher than weak or pale shades. Using highly controlled viewing conditions and color comparators, a fancy color grader selects one of 27 hues, then describes tone and saturation with terms such as “Fancy Light,” “Fancy Intense,” and “Fancy Vivid.” The system GIA developed for describing colored diamonds is used worldwide.

GIA offers two types of grading reports for colored diamonds. The GIA Colored Diamond Grading Report contains the same comprehensive diamond 4Cs information as GIA certification of D-to-Z diamonds while the GIA Colored Diamond Identification and Origin Report only includes the color grade and the origin of the color (natural or treated).

GIA certification is also available for colored gemstones like sapphires, rubies and emeralds, but these reports do not grade the quality of the gem. They confirm its natural origin, describe its color and whether of not it has been treated, and sometimes will also include information on where the gem was mined.