History and Significance
The tiara is most often demonstrated to be a symbol of Princess Diana's nobility, as Diana is one of only two Amazons depicted wearing regal headdress (her mother is the other.) Contrary to this when other's have won the right to represent the Amazons as Wonder Woman they have sometimes assumed the right to wear the tiara as well. The exact nature of the tiara was later discussed in an interview with Lois Lane after Diana and her mother relinquished their roles as royalty of Themyscira, in that it actually is a symbol of royalty. Following this period Diana wore her traditional costume yet without the tiara. Diana's entire costume including the tiara are often considered to be pro-American. However, the red star actually recognizes the sacrifice that Diana Trevor made in the defense of Paradise Island, as the Amazons honoured her sacrifice and assumed the flying insignia she was wearing were her battle colours.
There have been numerous occasions throughout the publication history of Wonder Woman when a tiara was not worn. During her depowered phase in the 1970s no costume at all was worn. In volume 2 from Wonder Woman #69, #70 & #71 she wears a modified headband while acting as a pirate in the deep reaches of outer space. From issue #93 to issue #100 of the second volume, Wonder Woman didn't wear the tiara as Artemis had assumed the title and role of Wonder Woman. At this time Diana wore a modified costume, still inspired by Diana Trevor's insignia though with a modified colour scheme. Also when Diana was deified following her death she wore no costume at all, but still wore a tiara, though not of the traditional design.
Use as a Weapon
The tiara is used on occasion as a ranged attack weapon, and with the combination of being very sharp and magical it can harm those who are otherwise impervious to physical damage. It has been used to decapitate Phobos and was used to cut Superman's throat when he was under Maxwell Lord's influence. Although often depicted as having the qualities of a boomerang, the tiara does not return automatically when thrown, rather it requires Diana to throw it in a specific manner.
Elseworlds and Alternate Designs
There were occasionally other explanations for its origin in the golden age. One of these said the tiara was an alien peace necklace, that Diana chose instead to wear as a tiara.
In the comic "Wonder Woman: Amazonia" her tiara has a Victorian decoration and is larger than the one which is regularly worn by the character. In the golden age the tiara is often shown as more of a headband than a traditional tiara shape (in that it wraps all the way around the head). Beginning roughly with the end of the depowered Wonder Woman reboot in Volume 1 Wonder Woman #204, Diana's tiara is displayed consistently as a traditionally shaped tiara.
Following the series reboot with Wonder Woman #600, Wonder woman has been given a new costume, partially influenced by her older costume. She still wears a tiara which has mostly the same motif except that the central portion over the face has the shape of a W.
Merchandise and Media Portrayal
On February 7, 2008, DC Comics had a promotional give-away metallic gold plastic Bronze Age style tiara. The tiara included a light-up star that could be activated with a flashing red LED light, depending of how you move it the star could be light up. Due to the success of the promotion DC Comics re-launched it again.
DC’s latest addition to the JLA Trophy Room was a replica of Wonder Woman’s gear which included tiara, two gauntlet bracelets and the Lasso of Truth.
The tiara’s measures were considerable big: 2.75" front top and 1.5" on the sides, 6.5" wide and 7.25" deep. The tiara had a gold-tone metal and the star had a translucent detail. The red star had bugle beads and a centered rhinestone giving it the bright red color.
During the production of Wonder Woman in the 1970's TV show multiple tiaras were made. Lynda Carter and Debra Winger worn the same tiara design. The tiaras had small pieces of Velcro so they could adjust them to their heads.
The tiara that Adriene Palicki wears for the never released Wonder Woman television show (2011) is very similar to the one we see in the new outfit worn by the character in the comics.