Black Icosahedron Approximately 10ft in Diameter

I was piloting a Cessna 172S at approximately 1,500ft flying a 1/4 mile off of the southern coast of Staton Island headed east towards the Verrazzano-Narrows bridge. As we were half way down the coast of Staton Island I noticed a black icosahedron shaped object. At first I thought it was a balloon, but as we got it closer it was clear that the faces and edges were extremely sharp and crisp and appeared metallic. While the object was primarily black, one of the triangles that made up the icosahedron was reflecting the sunlight and had a distinct purple hue. The object appeared stationary as we approached it, and it appeared to me to be a maximum of 10ft in diameter. I approximate our plane was 2,000ft from the object as I passed by it, however, this is judging by the speed it passed my wingtip assuming it was stationary. The object did not appear to have any rotation or movement.
I have attached an image I created after the incident that I think accurately captures what I observed. Again, this image is not a photograph of the event. It does not capture the purple hue of the sunlight reflecting off it, which was memorable as it helped me gauge the flatness of the surface and has led me to rule out it being a balloon. The actual edges were sharper than how it appears in the image I created.