Similarly other consort crowns of queens consort Mary of Modena and Adelaide of Saxe-Meiningen, the Crown of Mary of Modena and the Crown of Queen Adelaide, were made up of four half-arches, following British tradition.
The only example of a crown of a reigning British monarch possessing more than four half-arches is the Imperial Crown of India, made for King George V as Emperor of India to wear at the Delhi Durbar of 1911, and which had eight half-arches.
In contrast many European crowns traditionally contained many more, as did some other British consort crowns. For example The crowns of two 20th century British Queens consort, the Crown of Queen Alexandra (1902) and the Crown of Queen Mary (1911), reflecting their origins as European princesses from Denmark and Germany respectively, each had eight half-arches.
The Crown of Louis XV of France (1722), shown above, reflecting the European norm, has eight half-arches.
Different crowns possess different shaped half arches. In some crowns, the half-arches dip down at the centre of the crown where they meet the globe. The most widely recognized example of this is St. Edward's Crown, the British coronation crown, while in others, such as Queen Elizabeth's consort crown, all four half-arches rise at a somewhat right angle, with no central dip.
However, in the case of the State Crown of George I, while the crown as originally designed had dipping arches, they were pulled up to a right angle for the coronation of King George II and have remained in that position.
In some crowns, such as that of the Crown of Queen Elizabeth shown, the half-arches are detachable, allowing the crown to be worn as a circlet. Alexandra of Denmark, Mary of Teck and Elizabeth Bowes-Lyon (British queens consort Alexandra, Mary and Elizabeth) all at various stages wore their own crowns as circlets, particularly after the deaths of the husbands, when one of their children was on the throne and they were the Queen Mother.
Where a crown possesses arches or half-arches, the circlet of the crown below the arches or half-arches are usually filled with velvet or other cloth, or with a jewelled metal cap. Different states and different crowns may possess different coloured cloth inlays.
However not all crowns possess arches. The Danish Crown has no covering at all but exists in circlet form, while the Papal Tiara rises as one solid silver (or in one occasion gold) unit. Nor are arches to be found on the Iron Crown of Lombardy, any of the Iranian Crown Jewels. The Russian coronation crown possesses two central half arches, with most of the rest of the crown covered in. A same feature occurs on the mediaeval Crown of Rudolf II used by the Austrian Empire in the 19th century.