High Middle Ages
During the High Middle Ages, the Knights Templar were a fully public order, and their soldiers wore the insignia freely on their uniforms.
By the time of the Renaissance, in Italy, the Templars had gone into hiding and adopted more secretive tactics. As a result, their insignia was no longer displayed publicly, but was instead used only on relatively innocuous items, such as rings.
During the Industrial Revolution, the Templars once more displayed the insignia in public in the form of the logo for Crawford Starrick's corporations and his associates such as the Blighters gang. The high ranking Templars wore the insignia in the form of mantels and arm bands.
By the modern era, the Templars had largely removed themselves from the public eye completely; only certain members of Inner Sanctum of the Templar Order wore rings with the insignia displayed on them, even when amongst their brethren.