* Depth of the scratch: Shallow scratches tend to be red initially, while deeper scratches might have a darker red or even purple hue due to bleeding under the skin.
* Blood clotting: As the scratch heals, the color may change from red to brown or yellowish as the blood clots and dries.
* Skin pigmentation: The color of the scratch may appear slightly different on people with darker skin tones.
It's important to note that a fingernail scratch can also look white or silvery if it's very superficial and only affects the outer layer of skin.
In any case, it's generally advisable to clean and disinfect any fingernail scratch to prevent infection.