It's not the easiest metal to work with, my wedding band is Tantalum and they couldn't engrave it. Lol Tantalum is a chemical element; it has symbol Ta and atomic number 73. Previously known as tantalium, it is named after Tantalus, a figure in Greek mythology. Tantalum is a very hard, ductile, lustrous, blue-gray transition metal that is highly corrosion-resistant.
Here's a non expensive World Coin that I find Cool. The 5 Kings Coin Greece 30 Drachmai (Five Greek Kings) 1963
Post my favorite? That's like asking a teenage boy to post a photo of his favorite girl!.... But I always come back to this one. I am a seated lady lover and this one (my avatar coin) always makes me happy. I still don't believe that she resides in my collection. Thank you @C-B-D