Aqua aura is a term used to describe a natural crystal

Crystal

A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...

 that has been coated with gold fumes. It is created in a vacuum chamber from quartz

Quartz

Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...

 crystals and gold

Gold

Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

 vapor by a process known as vapour deposition. The quartz is heated to 871 °C (1600 °F) in a vacuum

Vacuum

In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...

, and then gold vapor is added to the chamber. The gold atoms fuse to the crystal's surface, which gives the crystal an iridescent metallic sheen. The process was awarded the United States Patent

Patent

A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

 No. 6997014 on 14 February 2006.

When viewed under a gemological microscope in diffused direct transmitted light, Aqua Aura displays the following properties:

• A coppery surface iridescence in tangential illumination
• Diffused dark outlines of some facet junctions
• A patchy blue colour distribution on some facets
• White facet junctions, irregular white abrasions and surface pits, where the treatment either did not "take" or had been abraded away.

Additional elements can be used to treat quartz, such as indium

Indium

Indium is a chemical element with the symbol In and atomic number 49. This rare, very soft, malleable and easily fusible post-transition metal is chemically similar to gallium and thallium, and shows the intermediate properties between these two...

, titanium

Titanium

Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

, and copper

Copper

Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

. The coloring of this treatment is only on the surface, so all faceted and polished material you find has been treated after it has been made originally. Often, quartz of lesser quality, with fractures and weak spots, will break apart during the coating process.

The aqua aura treatment can be used to reveal twinning

Crystal twinning

Crystal twinning occurs when two separate crystals share some of the same crystal lattice points in a symmetrical manner. The result is an intergrowth of two separate crystals in a variety of specific configurations. A twin boundary or composition surface separates the two crystals....

 in quartz crystals that would otherwise go undetected. While most treated quartz is destined for the metaphysical marketplace, it does have a use in the field of mineralogy.

Flame Aura

Flame Aura or Rainbow Aura Quartz

Quartz

Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...

 have been enhanced with a combination of titanium

Titanium

Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

 and niobium

Niobium

Niobium or columbium , is a chemical element with the symbol Nb and atomic number 41. It's a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite...

. Titanium molecules are bonded to the quartz by the natural electrostatic charge of the crystal in a process known as magnetron ionization. The brilliant color of Flame Aura is the result of optical interference effects produced by layers of titanium. Since only electricity is used to deposit the titanium layers and create these colors, very little heat is involved and the integrity of the crystal is maintained. The crystal does not become brittle or prone to breakage as with other enhancements. If it does however, the natural color of the stone will show through because the enhancement is only on the surface of the crystal.