The initial theory is that this encasement may mean the opal itself is opalized amber. Theoretically speaking, the insect likely was trapped in tree sap or resin which, over time and under the right circumstances, was preserved as amber with the insect encasement. This is a process many of us are familiar with. However, a second, much rarer process of opalization can also occur. And so, in this case, as conditions changed for the amber specimen, it is possible the amber opalized, preserving the inclusion. Amazingly, the silica surrounding the insect also structurally changed to produce the play of color.