I will assume when you say buffing dust that it is from carborundum wheels or buff sticks, this can be melted but incineration first would be a good idea, the next step is preparing the necessary flux followed by a long soak at high heat in a furnace, occasional stirring would also be beneficial, if done correctly you should recover 90-95% of the gold, in honesty wet refining would probably get a better return, once incinerated place into a beaker add distilled water, heat and add slow additions of nitric, this needs doing slowly until no reaction is visible, no fumes or bubbling in the solution, cool , filter and rinse well with distilled water, this should remove most of the silver and base metals, then return the remaining powders to the beaker add plenty of Hcl and heat then again slow additions of nitric, the gold should all be dissolved when after the last addition of nitric it produces no reaction but always add a little more Hcl and watch for reactions, cool and filter the solution and precipitate the gold with the method of your choice.
The silver can be cemented from the solution using copper
Be aware all dissolutions produce toxic fumes so they should be done using a fume hood.
Polishing dust needs incineration and is best recovered again using acids, the difference is that to make filtering easier you treat the powders with Hcl and then use AR, if you have volumes you need to boil the solution, use a watch glass and stir regularly to avoid hot spots and broken beakers, I'd suggest at least 6 hours on the heat.
Filter the solution once cool and use water washes to remove as much solution as possible, if done correctly you should recover 90% of the gold the first time, you need to decide if it's worth treating the powders again, as this is a first time processing this material I'd suggest a second treatment.
