Abstract: A ceramic casting shell is formed by a method comprising the steps of coating a wax former with one or more layers of a ceramic slurry; drying the or each layer of ceramic slurry; wherein the dried layer or layers of ceramic slurry form a ceramic shell; applying over the ceramic shell, a coating of a polymer material; heating the formed assembly to melt and remove the wax former, wherein the polymer coating acts as a strengthening layer to the ceramic shell during the wax removal process; and subsequent to removal of the wax former, heating the ceramic shell to melt and remove the polymer coating. The polymer coating is preferably the outer coating of the ceramic shell. The polymer coating may be applied by spraying, dipping or painting onto the ceramic shell.

Abstract: A pour cup assembly (10) includes a pour cup (12) of frusto-conical shape and which has an inlet end (14), of relatively larger diameter, and an outlet (16), of relatively smaller diameter. The assembly (10) also includes two yokes (18, 20) each including a body section (22) with a part frusto-conical internal profile and opposing arms (24, 26) extending laterally from the body section (22) and that lie in a common plan. Each arm (24, 26) has a bore or hole (30) therein. The body portion (22) has an external profile that is also part frusto-conical in shape and has one or more circumferential grooves (32) in its outer surface. The grooves (32) extend parallel to the arms (18, 20) and transverse to the longitudinal direction of the body portion (22). The grooves (32) in use accommodate a tie element disposed around the body portion (22) and cup (14) to hold the assembly together while the assembly (10) is subsequently coated with ceramic material to form the pour cup assembly.

Abstract: A pour cup assembly (10) includes a pour cup (12) of frusto-conical shape and which has an inlet end (14), of relatively larger diameter, and an outlet (16), of relatively smaller diameter. The assembly (10) also includes two yokes (18, 20) each including a body section (22) with a part frusto-conical internal profile and opposing arms (24, 26) extending laterally from the body section (22) and that lie in a common plan. Each arm (24, 26) has a bore or hole (30) therein. The body portion (22) has an external profile that is also part frusto-conical in shape and has one or more circumferential grooves (32) in its outer surface. The grooves (32) extend parallel to the arms (18, 20) and transverse to the longitudinal direction of the body portion (22). The grooves (32) in use accommodate a tie element disposed around the body portion (22) and cup (14) to hold the assembly together while the assembly (10) is subsequently coated with ceramic material to form the pour cup assembly.

Abstract: A kit for jewellery is provided including a support element 12, such as a ring shank, and a collet 14. The support element 12 includes facing support surfaces between which the collet 14 can be inserted in an insertion direction. The support element 12 and the collet 14 each include a guiding element 24, 16, one of which includes a ridge and the other of which includes an elongate recess. The ridge and recess are configured upon insertion of the collet 14 between the support surfaces to interlock to hold the collet in position; the collet 14 being removable from the support element 12 by manipulation solely of the collet 14 including pulling the collect 14 in a direction opposite to the insertion direction. Insertion and removal of the collet 14 causes no strain or no unrecoverable strain on the support element 12.

Abstract: A jewelry assembly comprises a shank (30, 70, 110, 156, 172, 198) and a collet (10, 50, 108, 150, 164, 186) and a locking element (26, 28, 46, 48, 64, 66, 92, 94, 105, 107, 152, 162, 166, 170, 182, 184, 196, 202) on each of the collet (10, 50, 108, 150, 164, 186) and shank (30, 70, 110, 156, 172, 198) arranged to mechanically cooperate to hold the collet (10, 50, 108, 150, 164, 186) and shank (30, 70, 110, 156, 172, 198) in a predetermined relative position. Two locking elements (26, 28, 46, 48, 64, 66, 92, 94, 105, 107, 152, 162, 166, 170, 182, 184, 196, 202) may be provided on each side of the collet which are rounded protrusions and which cooperate with corresponding holes in the shank.

Abstract: A jewelry item includes a support element provided with inner and outer zones, first and second support surfaces having a resilience and facing one another with a taper from the inner to the outer zones. The taper provides a bisector extending along the axis of taper. First and second spaced recesses or protrusions are provided on each of said support surfaces. A collet for holding a stone or other item having first and second collet surfaces complementary to the first and second support surfaces, said collet surfaces having a taper substantially corresponding to the taper of the support surfaces, each of said collet surfaces including first and second spaced protrusions or recesses designed to cooperate and fit together with associated recesses or protrusions of the support surfaces. Said collet being fittable to said support. Each of said protrusions includes a surface extending substantially transverse to said bisector.