I would trade you one-for-one, if you're interested. Otherwise, it doesn't seem equal since EHSP is going for 1900c (1720c after fees) on auction now (and I've sold it for more than 2000c in the past), while you'd only get 1600c for the diamonds from a street vendor. I'm not sure how much diamonds go for on auctions, but I doubt it would be much more than the EHSP after fees.
Just to be clear, I can make more than one EHSP to trade for more than one diamond. I'm just saying they are about equivalent in currant value.
I totally remembered wrong that EHSPs were 2000c because in my head they were 1500c. But yes, one for one trades!! I am definitely still down for that if anyone is!