Women have fought to straighten their curly hair for centuries, but the first patented flat iron is credited to Isaac K. Shero in 1909. Irons have been made with many different materials, most notably ceramic. More recently, manufacturers have begun using titanium, a metal, and tourmaline, a crystal, to help keep hair shiny and healthy as well as straight.
Both tourmaline and titanium flat irons heat quickly, but the titanium material heats more evenly, without cold spots. Titanium also retains the heat better, allowing for faster styling.
Tourmaline naturally produces negative ions when it is heated, and negative ions and far infrared rays are what helps hair look shiny without damage. Ceramic also produces negative ions, which is why titanium is often combined with ceramic.
Titanium is as strong as steel and doesn't corrode. Tourmaline is a gemstone and can wear faster than titanium. Both materials are normally ground down and infused into the flat iron plates, which is why most of the irons with the materials are marketed as nano-titanium or nano-tourmaline.
Tourmaline works fine to straighten most hair, but titanium is the choice for hard-to-straighten hair. Both work far better to keep hair straighter longer than ceramic or aluminum plates.
The cost varies by manufacturer, but adding tourmaline, titanium or both to a flat iron definitely makes the unit more expensive than ceramic irons. Many with either tourmaline or titanic retail from $70 up to $180, as of time of publication.