Solid objects are almost never made of rhodium. Instead, it is used to plate inexpensive jewelry pieces to give them a shiny surface.
Rhodium is the most expensive of the precious metals. Its value fluctuates wildly with variations in supply and demand. Until recently, rhodium spot was over $5000 per ounce. The price plunged in 2009, but a rhodium coin is still pricey because it is a hard and brittle element, thus difficult to make into a coin.
A unique fantasy piece struck in Rhodium for Reginald Huth by Pinches & Company between 1892 and 1904. The Huth collection was sold by Sotheby & Company in 1927, and since then the fantasy nature of these coins has been forgotten, as they occasionally surface as "patterns", which of course they are not. Huth had pieces struck in Gold, Palladium and Iron. A similar coin with a different reverse was struck in Platinum, Gold, Iridium and Iron.
In an email to me, Eitan Cohen of The Cohen Mint had this to say about the Huth fantasy coins:
"I am skeptical as to its true composition. Making coins out of this metal is extremely difficult and requires a very specialised manufacturing process. What reinforces my skepticism is the comment that he struck coins out of iridium as well. I have successfully made blanks out of iridium (.999 fine) but found that it simply does not flow into a die, no matter how I try and coax it. It simply snaps, shatters and breaks, even more so than rhodium tries to. I am experimenting with ways of placing a design onto the blanks without striking in a coin die. My guess, based on my personal experience working with these metals in their pure form is that if there is any truth at all, then the most likely explanation is that the coins were made from an alloy containing these metals, however not in their pure form."
Pictured above is the Cohen Mint's first pure rhodium bullion coin: 1 gram, 12.9mm. The 2009 design shown had a total mintage of 39,542. A much fuller, frosted three-dimensional design has been created for 2010. According to the Cohen Mint website they plan to produce rhodium coins in larger sizes, as well as bullion bars and solid rhodium jewelry, and they are experimenting with test strikes in other metals such as iridium, rhenium, and ruthenium.
So who made the first pure rhodium coin? To be honest, I don't know. I had emailed Dave Hamric as early as December 2008, and he replied that "a die is made and I'm having pellets made to try making blanks." His first successful strikes were in March 2009, they were released on May 28, and the first shipment was June 30.
On the other hand, Mr. Cohen states he "manufactured the first pure rhodium coin 4/29/09", his website shows two media sources on May 22 reporting that the coins would hit the market "within the next few weeks", and also that "the Cohen Mint first created and released the Genuine 1 gram Rhodium Coin back in June of 2009"
That's too close for me to call. However, the Cohen Mint's offering is definitely the first pure bullion rhodium coin, because the coin is marked with both the fineness (999) and the weight (1 gram).