How much gold would I have to hock up to get 800 diamonds?

Depends on what's going on when you buy. An eggling auction will generally decrease the cost of diamonds. A really amazing monthly or great discounts in the diamond shop will generally increase the cost of diamonds.

Most of the time, with nothing exceptional going on, diamonds seem to sit in the range of 2,500 - 3,000 each. So 2m - 2.4m.

My recommendation would be to keep an eye on the Currency Exchange, in particular what people are selling gold for - that'll give you the best idea as you probably won't be able to get your diamonds for less than what others are willing to pay for diamonds at that time.

If you're patient and comfortable to wait, you could pick what amount per diamond you're most comfortable with. If, for example, it was 2,500 per diamond then you could just continue to put up an offer to sell 2m gold for 800 diamonds until the market moves in your favour.

Normally I sell 1800g for 1 diamond. Offer gets accepted within 5 days @ most. If you're urgent then 2k for 1 diamond.

If you buy diamonds with gold (not selling gold for diamonds), the cost per diamond is higher (usually)

Ok, thanks! :)