Jennifer Lopez's main accessory lately isn't a necklace, ring or even a handbag -- it's a crystal-covered Starbucks cup, and it's about to make one designer a butt load o' dough.
TaylorMade Bling founder Teneka Moore tells TMZ ... she thought she was getting punked when J Lo's manicurist asked her to make the bedazzled cup as a b-day gift for Jennifer.
It's obviously a huge hit -- the glam mug, encrusted with Swarovski crystals, has been with Jen almost as much as Alex Rodriguez. Moore says J Lo's cost $585, and A-Rod got his own last month for $495.
We're told other celebs have been reaching out too, which means Moore's holiday season could be very green.