A crystal of zircon (zirconium silicate) contains trace amounts of uranium which decay radioactively to lead, and can have several concentric zones of growth of different ages. The Sensitive High Resolution Ion MicroProbe (SHRIMP) technique uses a double-focused high-energy ion beam and mass spectrometer to determine the age of a tiny area (<30 µm diameter) of a single crystal.
Engagement rings with zircon
Look sparkling and attractive
But zircons trap uranium
Which makes them radioactive.
So do SHRIMP-date your zircon
On the day that you get wed –
Then check again in fifty years
In case it’s full of lead. . .