Fabian,
It uses Arial, specifically the 'black star' (Unicode 0x2605) and "middle dot" (Unicode 0x00B7) characters.
For Dark UI:
When a rating is on, it is drawn with the color 155,159,165 (alpha 255)
When a rating is off, it is drawn with the color 210,210,210 (alpha 120)
For Light UI:
When a rating is on, it is drawn with the color 0,0,0 (alpha 255)
When a rating is off, it is drawn with the color 64,64,64 (alpha 100)
If for some reason your Arial font does not have those characters, I would still expect the numbers to be drawn.
-Kirk