Question about a dark spot on a white gold band

[tylerm]

As people don''t make white gold forums, I figured this is the best place to ask. I have a question for anyone who''s experienced with such things. I bought an engagement ring for my fiancee close to a year ago, with the band made of white gold. It looked lovely, but a few months after she wore it, a darker spot (sort of greenish-brown) about 1mm X 2mm appeared on the band. We took it back to the jeweler, who said something must be on it, and he polished it quickly, and it looked good as new. But a couple months later, the spot came back in the exact same place.
It''s on the underside of the band, but a good ways off center, so we''re sure it''s not from rubbing on things she''s holding. To the eye, it appears flush with the metal, and isn''t affected by scratching at it with a fingernail, etc. Is this an actual flaw in the metal? I''m confused as to why it went away with a quick polish, but returned. Any ideas?

 

[chrono]

Has the ring been exposed to chlorine? Discolouration from chlorine can be buffed away but I am more concerned with it affecting the integrity of the gold.

Or perhaps her body chemistry is reacting with the nickle in the white gold?

 

[EstateJeweler]

There are several things that can cause a dark spot. First, all white gold and platinum jewelry is plated with rhodium prior to leaving the manufacturer. As you know, gold is yellow and platinum is greyish (like pewter). The yellow gold is mixed with nickel to make it white(ish). The white gold will have a yellowish hue to it until it is plated with the rhodium to give it a shiny silvery finish. If the plating wears off or it was plated with contaminated rhodium then it is possible to get a blemish like yours. Sometimes the caster will use contaminated/dirty gold. This can cause another problem called porosity. Porosity will cause small voids in your metal that resemble the holes you get in a pancake during the cooking process. There is nothing that can be done for this problem. If your ring continues to get blemishes then you should go back to your jeweler and tell him to make it right.

Russell