London, Victoria and Albert Museum (4-1865): Casket of William de Valence, Limoges or England, late 13th c.
Copper engraved and gilded, decorated in champlevé enamel (8.8x17.6x13.3cm)
Arms: England: gules 3 leopards (lions passant guardant) or; Valence (Earls of Pembroke): barry of 12 argent and azure, an orle of martlets gules; Dreux/Britanny (cf. Alix de Dreux): chequy or and azure a bordure gules, overall a canton ermine; Angoulême (Isabelle of Angoulême, widow of King John, m.2. Hugues de Lusignan): lozengy gules and or; Brabant (for Margaret, daughter of Edward I, who m. Jean de Brabant in 1290): sable a lion rampant or; Lacy (Earls of Lincoln): or a lion rampant purple (cf. Falkirk's Roll 1, ed. G.R. Brault, Eight Thirteenth-Century Rolls of Arms, University Park and London, 1973, p. 86).

Thought to be a wedding gift from William de Valence (d. 1296) (Earl of Pembroke, half-brother of Henry III through his mother Isabelle of Angoulême and her second husband Hugues de Lusignan), to his son Aymer (d. 1324) in commemoration of the latter's marriage at an  uncertain date to Beatrice-Jeanne de Clermont-Nesle (she d. 1320, whereupon Aymer m. Marie comtesse de Saint-Pol, foundress of Pembroke College, Cambridge).  If so, then why aren't the arms of Clermont-Nesle (gules sown with trefoils or, overall 2 barbels addorsed or) on it ?   I suspect it was made for William himself and is earlier than had been thought--though if before 1290, the Brabant arms must be explained.  The Lusignan arms are similar to Valence minus the birds.  William m. c. 1247 Joan de Munchensey, granddaughter of William Marshal, First Earl of Pembroke (his arms party per pale or and vert, a lion rampant queue forchée gules (Tremlett, ed. Matthew Paris Royal 14.C.VII, no  29)); Munchensey is or three escutcheons vair  (ibid. p. 76) with variants.

cf. William de Valence's tomb in Westminster Abbey, also done in enamel and originally bearing these shields (several of the tomb shields are now destroyed, but they are reproduced in C.A.Stothard, The Monumental Effigies of Great Britain, London, 1817, nos. 44-45, pls. 41-43)
cf. the hanap cover at All Souls College Oxford (now on deposit at the British Museum), made for Raoul de Nesle (d. 1302), father of Beatrice-Jeanne, who married a second wife, Isabelle of Hainaut, in 1297 (Art and the Courts, no. 56; L'art a temps des rois maudits: Philippe le Bel et ses fils, ed. D. Gaborit-Chopin, Paris, 1998, no. 135)

References:
Art and the Courts, ed. Marie Montpetit, Ottawa: National Gallery, 1972, no. 51
Frick N6843 V37 1972

Gauthier, M.-M  Émaux du moyen âge occidental, Fribourg, 19, no. 143
Frick NK5013.5 .G27

Williamson, Paul.  The Medieval Treasury: The Art of the Middle Ages in the Victoria and Albert Museum, London: V & A, 1986, p. 195
Frick N5964 G7L66 1986

Age of chivalry : art in Plantagenet England, 1200-1400 / edited by Jonathan Alexander & Paul Binski, London, 1987, no. 362
Frick N6763 A43 1987