Your outfit should not match your show halter. How weird would it be for people to have light oil or dark oil colored show clothes? Hehe So you're fine there. About the halter being silver and gold, I assume that you mean the silver bars have a gold design of some sort? That is fine too. There are a lot of show halters out there with gold or colored crystals on them. From the sound of it, you have nothing to worry about. Although, for a typical stock type (AQHA, APHA, ect.) halter class you wouldn't wear gloves. And don't forget to wear a hat!
Keep your personal colors more muted and perhaps chose something that complements the horse's color. First impression goes a long way with the judge so don't crowd the horse in front and smile at the judge out of courtesy. Be sure you and your horse are polished to the nines. I know it's a halter class but it's nice to have the judge think favorably of your appearance.