Thank you for your question. I cannot imagine a black glove being a problem, as what is prohibited is anything used to distract the batter. A black glove would be pretty standard.
That being said, however, I would go speak to your local high school coach and ask his/her opinion. The coach should be familiar with both the state and and the rules for the league taht they play in. Also, you may want to check the rules for the California state athletic commission if you do not want to speak with the coach. Speaking to the coach is the easiest option.