GIA diamond gradings generally look like the below image showing the 8 distinct sections we'll cover in more detail below. Each report has a special ID number that is listed at the top center of the certificate under the words "GIA Report" and on the left hand side in the section titled GIA Natural Diamond Grading Report (#1 below). This GIA number is unique to each diamond and is often laser inscribed on the side of the diamond in tiny print along the diamond's girdle.

Take the below report which comes from this diamond (GIA 2416541737) available from Blue Nile. We've added notation that will help us study the report easier as we go...

1. Basic Diamond Information of the GIA Grading Report
The first section of the report on the left hand side provides some basic information including:

GIA Report Number: your diamond's unique identifier which ties the physical diamond to the GIA's grade for the stone

Shape & Cutting Style: describes the diamond's appearance both in terms of shape (round, oval, pear, etc.) and cutting style (some shapes like cushion cut diamonds have a variety of styles such as Brilliant, Modified Brilliant, and Old Mine Brilliant)

Measurements: these list the length, width, and depth of your diamond in that order. Diamond measurements shown are in millimeters.
Advice: The shape and cutting style of your diamond are totally a matter of preference. Some people love round cut diamonds (the most popular diamond shape by far) while others prefer more exotic shapes like marquise or asscher cut diamonds.

The dimensions are a matter of preference as well, but there are some fundamental issues with a diamond being too deep or too shallow (high depth relative to length and width), or having too elongated of a shape (high length relative to width). Each diamond shape is different but generally speaking our visual carat weight score will catch any major issues with these dimensions. You can check it for any GiA ID by using our GIA Check Tool to query your diamond.