This is a bit tricky. It's common to use:

• Prata for both masculine and feminine words (o carro prata e a bolsa prata)
• Prateado for masculine words (o carro prateado)
• Prateada for feminine words (a bolsa prateada)

Prateado and prateada is a bit more "elegant" and correct, but it's very common to find both ways. Feel free to use any form.

Masculine: branco (o carro branco)

Feminine: branca (a bolsa branca)

Same for masculine and feminine words: verde

Same for masculine and feminine words: transparente (o vidro transparente e a bolsa transparente)

Same for masculine and feminine words: laranja (o carro laranja e a bolsa laranja)

Masculine: amarelo

Feminine: amarela

Masculine: preto

Feminine: preta

Same for masculine and feminine words: marrom (o carro marrom e a bolsa marrom)

Same for masculine and feminine words: violeta (o carro violeta e a bolsa violeta)

Masculine: roxo (o carro roxo)

Feminine: roxa (a bolsa roxa)

Many people in Brazil do not know the difference between roxo, lilás and violeta

Same for masculine and feminine words: bege (o carro bege e a bolsa bege)

Masculine: vermelho

Feminine: vermelha

Masculine: rosa (o carro rosa)

Feminine: rosa (a bolsa rosa)

Masculine: dourado (o carro dourado)

Feminine: dourada (a bolsa dourada)

Dourado comes from de ouro (or d'ouro, from gold).