Just to share some info, for TE37, there are only 2 standard colour you can order, its bronze and white.
As for gunmetal and flatblack, all are custom colours u ordered from RAYS on a special basis, it will take ard 3 months for them to do in these colours.
From wat i know, all the Rays rims i ordered, RE30 and Te37, my TE37 cames with stickers in flatblack.
Just to add, you have to pay extra to get them in any colour but bronze and white