It is a known fact that the cut, clarity, carat, and color affect the pricing and value of diamonds to a great margin. However, when it comes to colored diamonds, the intensity of the color and fluorescence also play a part in determining the overall value of the fancy diamond engagement ring.
Usually, natural fancy orange diamonds have a clarity grade that falls within VS1 to I1. Although some of the colored diamonds might go below this clarity range, the vibrancy of the orange hue can hide the flaws in the stone perfectly, which would have been otherwise visible to the naked eye. The extent of color spread in the stone also counts here.
A uniform and even color distribution in an orange diamond will make the stone appear almost flawless. Oftentimes, this leads to confusion among buyers, as a deep colored orange stone might not have the clarity as stated by the seller. This is why it is recommended to consult with an expert gemologist while buying a fancy diamond engagement ring. Additionally, you can go through the GIA report accompanying the diamond to make sure that the color specifications and the clarity grading mentioned are accurate.
Note that the fluorescence in orange diamonds gives it a medium to deep yellow glow under ultraviolet light. So you can also check for that to ensure that your stone is real and has its trademark golden luminosity.