Nitrogen-vacancy (NV-) color centers in diamond were created by implantation of 7 keV N 15 (I=12) ions into type IIa diamond. Optically detected magnetic resonance was employed to measure the hyperfine coupling of single NV- centers. The hyperfine spectrum from NV-15 arising from implanted N15 can be distinguished from NV-14 centers created by native N 14 (I=1) sites. Analysis indicates 1 in 40 implanted N15 atoms give rise to an optically observable NV-15 center. This report ultimately demonstrates a mechanism by which the yield of NV- center formation by nitrogen implantation can be measured.