There are two stable isotopes of carbon. If natural carbon consists of $98.938 \%{ }^{12} \mathrm{C}$ and the accepted atomic mass of carbon is $12.0107 \mathrm{u}$, what is the isotopic mass of a ${ }^{13} \mathrm{C}$ atom? Diamond is made of pure carbon and has excellent mechanical, electrical, and light transmission properties. Recently, scientists made some diamonds out of ${ }^{13} \mathrm{C}$ and found that they had even better physical properties than "normal" diamonds do.