Re-hosting this question from Physics to Chemistry, lightly edited.
Rubies and sapphires are chemically equivalent to the mineral corundum, with the exception of transition metal impurities that impart different colors to the aluminium oxide. Uranium is not a transition metal, but it can be used as a coloration admixture with silicon dioxide, and exists in various oxide forms.
Can uranium be used as a coloration impurity for 1) aluminium oxide based gemstones and/or 2) diamonds? If uranium cannot chemically bond with the substrate, then the ability to produce a consistent heterogeneous mixture, e.g. by suspending uranium oxide dust in molten aluminium oxide during the process of flame fusion would be a satisfactory answer in the affirmative.