Jewels like these were very expensive at the time this thread was posted simply because they were extremely rare.
I remember I myself paid 500mil for a simple 15HCI/10ssi brace 1 and a half years ago.
After Global Loot was introduced, 1 or 2 mod jewels like these became easier to get, thus price have fallen drastically.
You can buy the same jewels for around 20-30mil these days.
This is one of the best examples how just one publish can drastically change price of a particular item.