Black and White Is Allowed
Written into the requirement, not an oversight.
The requirement opens by saying the photograph is placed on the application "in black-and-white or colour", at 35 x 45 mm. Both are permitted, in that order.
This is genuinely unusual. Most countries that once accepted monochrome removed the option when biometric checks arrived, and plenty now reject it outright — Russia's own e-visa guidance asks for natural skin tone, which effectively means colour.
You would still normally submit colour. The point is that a black-and-white print is not a reason for refusal here, which is worth knowing if that is what a studio hands you.
