The Gübelin Gem Lab discovered an exciting effect in a sapphire from Elahera (Sri Lanka). The stone contains several large negative crystals. These are cavities in Sapphire, who have taken over the shape of the crystal. Two of these negative crystals are filled with a liquid and a gas of yet unknown composition.
With gentle heating by a few degrees Celsius, the liquid in the right inclusion begins to boil. The bubbles are formed on the surface of a black crystal, which could be graphite. Simultaneously, the gas quantity decreases more and more. Since the system is closed, the gas dissolves in the liquid.
After a very short time, the negative crystal only contains a homogenized liquid. In the left negative crystal the free gas fraction increases with the heat. Presumably, the complete liquid transforms into gas, so that after a few seconds, the liquid completely disappears.
Once the stone cools, the process is reversed. First tiny droplets are produced in the left inclusion that transform in a very short time into a coherent liquid. Shortly thereafter the first bubble arises in the right cavity, starting from the black crystal.
After the stone has cooled down to room temperature, the initial state (liquid with one / two gas bubbles) is restored. In science, this effect is used to determine the minimum temperature of the crystal formation.
Apart from the scientific evidence this video is a fine example of the wonders and phenomena that can be hidden in gemstones.