It depends upon your definition.
According to 2008 CMG - goldust is either ultramel caramel or homo ultra caramel. From what I understand, it only includes them both because if you have a clutch that can produce both ultras and ultramel - there is no reliable way to tell them apart.
Apparently you can make good guesses most of the time, but not perfectly.
Classic gold dust definition I believe was Caramel Ultramel which would mean that yes, a gold dust carries the amel gene.
If you expand gold dust definition to include caramel ultra than an ultramel may or may not carry the amel gene (but always carries at least one copy of the ultra gene).
So - ultramel X ultramel if both carry 1 copy of the amel gene and 1 copy of the ultra gene would result in:
~ 25% caramel amel (butter)
~ 25% caramel ultra
~ 50% caramel ultramel (gold dust)
You won't be able to reliably tell the 25% caramel ultra from the 50% caramel ultramel. Some experienced breeders may guess right most of the time, but apparently none can guess right all the time.
Butters, if produced, should be easy to distinguish.
-----
Arrrggg!
It's like Shalom, but for pirates.
- iCarly