First: "Possible"
1. You are in the main menu of Hearthstone.
2. Right bottom of the corner you see your amount of Gold.
3. If you click on "My Collection", you will now see you Durst, where your Gold was before.
4. The Theory: I'm Currently on a very low pc, and when I click on my collection, the Amount of Gold is changing to the Amount of Dust I have, but the Symbol is still the same (the gold symbol) - few ms later, when I'm actually in my Collection, the symbol is now correct (the dust symbol).
So in the end, there is a small window where your gold amount = dust amount, but i dont know if we can use this or if its client side only.