The shield is surmounted by a closed crown, which is a circle of gold, inset with precious stones of their colours, composed of eight rosettes of acanthus leaves, of which five are visible, interspersed by pearls in their colour, issuing from which are four pearl diadems, of which three are visible, which converge in a blue orb, with gold semi-meridian and equator, surmounted by a gold cross, the crown lined with red and surrounded by the collar of the Golden Fleece.
The current holder has a lozenge (female) variant of the coat of arms adopted in 2001. It hasn't official status but it is attributed by some heraldists until the Princess can use the official coat of arms as Princess of Asturias in her own right and dame of the Golden Fleece.
Before 2001, the heir or heiress to the Spanish throne used this coat of arms unofficially, and still does in Aragon or Navarre, where a different version of the coat of arms, as Prince or Princess of Girona and Viana respectively, is displayed. It is likely that these arms will also be some day adopted officially.
Variants of Historic Titles of the Spanish Heir Apparent
The arms used in the 13th and 14th century by the Prince of Asturias, and the others heirs apparent to the Castilian Throne before the title was adopted, were the undifferenced Royal Arms. However, the Infantes used differenced arms.
When the House of Habsburg inherited the Crowns of Castile and Aragon marks of Cadency – a label of three points – were added to the heirs apparent's arms, as was usual in the heraldry of many European monarchies. Prince Charles (Charles I as King of Spain and Charles V as Holy Roman Emperor) used his father's arms – A quartered shield, depicting Austria, new Burgundy, old Burgundy, Brabant and Flanders on an escutcheon – with a label argent. These arms weren’t used as Prince of Asturias because Prince Charles didn’t add the arms of Castile and Aragon.
Prince Philip (Philip II as King of Spain and Philip I of Portugal) used his father's arms differenced with a label argent or azure. The Prince Philip's arms are showed on many Prince's armours. Now these armours have been kept at the Royal Armoury in the Royal Palace of Madrid. Sometimes, Philip also used the undifferenced arms of his father.
In 1568 Prince Carlos, the eldest son of Philip II, died and an Ambrosio Morales's report for the Prince's sepulchre said his arms were the Royal Arms but with "a label azure with its three short points". Prince Carlos also used the royal arms differenced with a label argent.
Prince Philip (Philip III as King of Spain and Philip II of Portugal) sometimes used a new label argent variant wavy azure.
The eldest son of Philip III, Prince Philip (Philip IV as King of Spain and Philip III of Portugal), used the Royal Arms with label argent or azure. Philip's son, Prince Balthasar Charles also bore the same differences.
The shields of the House of Bourbon's heirs apparent hardly ever depicted differences. Chronicler King of Arms Juan José Vilar y Psayla (1830–1894) said the arms of the Prince of Asturias were differentiated by a crown of four-half-arches, the Spanish monarch's crown has eight-half-arches since the reign of Philip V (1700–1746).
On sepulchres of Habsburg Princes of Asturias who didn't ascend to the throne their coats of arms are the undifferenced Lesser Royal Arms (Quarterly, 1 and 4 Castile, 2 and 3 León), with a crown closed with four-half-arches in crest. The Pantheon of the Princes of the Royal Seat of El Escorial was completed in 1888, in the nineteenth century the heir to the Spanish throne used Royal Arms differentiated by a crown of four-half-arches.
^Isabel la Católica en la Real Academia de la Historia. Madrid: Real Academia de la Historia. 2004. p. 72. ISBN84-95983-54-0.
^Princess of Isabella's coat of arms with crest: García-Menacho Osset, Eduardo (2010). "El origen militar de los símbolos de España. El escudo de España" [Military Origin of Symbols of Spain. The Coat of Arms of Spain]. Revista de Historia Militar (in Spanish) (Instituto de Historia y Cultura Militar) (Extra): P.387. ISSN0482-5748.