When Cartier introduced the Ballon Bleu in 2007, it reimagined the traditional round wristwatch. Rather than relying on conventional case geometry, Cartier created a softly curved silhouette, with its signature blue cabochon crown nestled inside a protective arch. Reference WE900951 elevates this contemporary design through an 18K white gold case and a double row of brilliant-cut diamonds surrounding its silvered dial. It is a meeting of Cartier's two historic disciplines: fine jewelry and watchmaking. The result is a timepiece that combines the presence of a substantial 42 mm case with the elegance of the Parisian jewelry house. table {mso-displayed-decimal-separator:"\."; mso-displayed-thousand-separator:"\,";} tr {mso-height-source:auto;} col {mso-width-source:auto;} td {padding-top:1px; padding-right:1px; padding-left:1px; mso-ignore:padding; color:black; font-size:11.0pt; font-weight:400; font-style:normal; text-decoration:none; font-family:"Aptos Narrow", sans-serif; mso-font-charset:0; text-align:general; vertical-align:bottom; border:none; white-space:nowrap; mso-rotate:0;} .xl100 {text-align:left; border:.5pt solid black;} Reference WE900951 Collection Ballon Bleu de Cartier Collection introduced 2007 Case 18K white gold Diameter 42 mm Bezel Two rows of diamonds Dial Silvered, Roman numerals Hands Blued steel, sword-shaped Crown Blue cabochon Movement Automatic, caliber 049 Power reserve Approximately 42 hours Functions Hours, minutes, seconds, date Crystal Sapphire Caseback Solid Water resistance Originally rated to 30 m Strap Alligator leather Clasp 18K white gold deployant