I am not sure about Photo, not used it too much. But if you can get to the Red/Blue/Green and the Hue/Saturation/Lightness controls of a color, I used these as bases in Paint.
Copper = Red/241 Blue/149 Green/173 Hue/11 Sat/196 L/195
Brass = Red/226 Green/198 Blue/102 Hue/33 Sat/174 L/164
Gold = Red/217 Green/203 Blue/173 Hue/29 Sat/84 L/195
Silver = Red/Green/Blue/230 Hue/255 Sat/0 L/230
Unfortunatley Silver is always going to tend to be on the Light Grey side.