For a long time I had all sots of pretty multicolored dice -- transparent, sparkly, iridescent, pearlescent, mottled -- until I realized that I couldn't read the numbers on most of them. So, my wife took all the prettiest ones, and the rest went into a "communal dice" box, for players who forget their dice.
Then I started over. Now, my wife thinks I have boring fuddy-duddy dice... The only ones I buy are monochrome -- white on black, black on white, white on mottled black/grey, or black on mottled white/grey. Nobody else, in our group at leat, uses those colors, and they're easy for me to read even from half the table away.
I like having the four different color combinations to distinguish between rolls when I'm rolling for multiple checks and/or (non-player) characters.