Luxman 509x white vs blue meters

Anyone know why there are units with white meters and others with blue?  I read somewhere that 509x has white, lower AB models blue, and class A amber.  Mine are white as well, but then I watched a YouTube video from a US-based channel with a blue meter 509x.  So I guessed that they were initially made with blue and later switched over to white.  But looking at past ads I see both blue and white going back to 2019.  So what gives?

Honestly I would love one with blue meters.  Not only do I think it looks better but white is pretty bright!  With the lights in the room off they are almost like flashlights.