Ancient Greece was a center of innovation and advancement during antiquity. Geometry, astronomy, logic, rhetoric, and a host of other fields of study were largely invented by the ancient Greeks. They did not invent the idea of coins, although the Greek city-states were known for their silver coinage, drachms, as they became more integrated into trade in the ancient Mediterranean world.
The Greeks also struck their own gold coins, a practice they picked up from their close neighbors. One notable example was the gold stater, a denomination of gold coin that (with some variance, of course) was used across the region -- by the Ionians, the Lydians, the Assyrians, and on and on. Finding one of these two-thousand-year-old gold coins is difficult, and anyone who loves ancient coins is proud to have a gold stater in their collection!
Not only do these gold coins come to use from the time before Jesus, but they have also been authenticated and graded by Numismatic Guaranty Corporation (NGC). This gives you the assurance and peace of mind that the ancient coin you're buying is certified as real.