Canary-coloured diamonds are typically graded based on the intensity and purity of their yellow colour, with the most desirable stones displaying a deep, saturated yellow without any secondary hues. The colour of a canary diamond is determined by the presence of trace amounts of nitrogen in the diamond's crystal lattice. Nitrogen is the most common colour-causing element in diamonds, and when present in sufficient concentrations, it can produce the yellow colour characteristic of canary diamonds.
The value of a canary-coloured diamond is determined by a number of factors, including its carat weight, colour intensity, clarity, and cut. Larger carat weights and more intense yellow colours are generally more valuable, as are diamonds with higher clarity and better cuts. Canary diamonds with a Fancy Vivid or Fancy Deep Yellow colour grade are considered to be the most desirable and command premium prices.
Overall, canary-coloured diamonds are highly sought-after by collectors and jewellery enthusiasts alike, due to their rarity, beauty, and unique colour.