Setting for a polished gemstone, semi-finished product of such a setting and method for manufacturing the semi-finished product

Abstract

A setting (1) for a polished gemstone (3) having a girdle (6), comprising a plurality of prongs (2) which together encircle the gemstone (3), wherein the prongs (2) hold the gemstone (3) by virtue of their inherent elastic spring force through a suitable choice of material and shape, characterized in that the prongs (2) together form a plurality of ribs and extend from a base plate (4), the dimensions of which, viewed from above, are smaller than those of the gemstone (3), in a frustoconically widening surface towards the gemstone (3) and hold it at their free ends under mechanical tension with spring force by means of hooks (5) directed towards the gemstone (3), wherein the base plate (4) and the prongs (2) are formed in one piece, wherein the spaces between the prongs (2) widen from the base plate (4) towards its free ends.

Description

[0001] The present invention relates to a setting for a cut gemstone, which may be a precious stone, a semiprecious stone, a glass stone, a synthetic stone, or the like, having a plurality of prongs that collectively enclose the gemstone. The invention further relates to a semi-finished product of such a setting and a method for producing such a semi-finished product. Such a setting is known, for example, from German utility model DE 71 26 182 U.

[0002] This type of stone setting, also known as a prong, chaton, or claw setting, is one of the most common gemstone settings. This type of prong setting has the advantage of being very delicate, making it barely visible and allowing plenty of light to shine on the gemstone, allowing it to unfold its full radiance.

[0003] A prong setting looks like a basket and is usually made up of several parts that must be joined together manually or by machine, which is a costly and time-consuming process. The setting usually consists of four, six, or eight bars, also called prongs, which are attached to a main body by soldering. The prongs are usually made of a precious metal such as gold, silver, or platinum and are either mechanically or manually struck or driven over the girdle of a cut gemstone. This means that the prongs are bent inward towards the stone until their claws or hooks rest against a girdle, which is usually present on a cut gemstone, thus securing the gemstone in place.

[0004] Bending the prongs represents a permanent, plastic deformation. This step requires considerable experience and very precise working techniques to avoid damaging the gemstone. Furthermore, simply attaching the prong hooks to the gemstone does not always guarantee that it is securely and without play.

[0005] DE 20 2014 006 869 U1 discloses a frame with the features of the preamble of patent claim 1. This frame is suitable only for rings, since the ring is functionally part of the frame.

[0006] DE 10 2007 035 690 A1 describes a carrier strip for holding, for example, decorative elements, which is produced by punching and bending a strip material and has deflectable holding arms for the decorative elements.

[0007] DE 100 35 158 A1 shows a setting for gemstones which is made up of two parts, whereby a semi-torus-shaped ring is clipped onto a spring-hard, multi-slit base part and a gemstone is clamped between them.

[0008] From DE 10 2004 053 381 A1 a receptacle for the releasable fixing of a decorative element is known, which has parts that enclose the decorative element in a form-fitting manner and are movable against a restoring force into a releasing removal position.

[0009] The Swiss patent CH 504 185 A shows a ring consisting of a springy metal strip, the central part of which is bent in a ring shape and the end regions of which are shaped to form four prongs that hold a gemstone.

[0010] The present invention is based on the object of improving a setting for a cut gemstone of the type described in the preamble of patent claim 1 such that the setting of the gemstone can be carried out more securely and easily and that the setting encloses the gemstone reliably and firmly. Furthermore, a one-piece semi-finished product for producing such a setting and a method for producing such a semi-finished product are to be specified.

[0011] The cut gemstone does not necessarily have to be a faceted gemstone such as a brilliant cut, but rather all types of cut stones, preferably with a concentric cut such as a cabochon, can be used for the present invention.

[0012] These objects are achieved by the features of claims 1, 4 and 7.

[0013] Subclaims are directed to preferred embodiments of the present invention.

[0014] The basic idea of ​​the present invention is that the prongs of the setting according to the invention, through the choice of their material and shape, are able to hold the gemstone to be set by their own elastic spring force.

[0015] Further advantages and features of the present invention will be explained in more detail by describing an exemplary embodiment of a brilliant-cut gemstone with reference to the drawings. Fig. 1 a semi-finished product for producing a gemstone setting according to the invention; Fig. 2 an embodiment of a gemstone setting according to the invention; and Fig. 3 which in Fig. 2 shown setting with an inserted cut gemstone with brilliant cut.

[0016] Fig. Figure 1 shows a semi-finished product 1a for producing a setting 1 according to the invention for a cut gemstone 3. It is made of a material with high elasticity. Stainless steel is particularly suitable for this purpose; however, other materials that allow elastic, springy deformation are also possible.

[0017] In the example shown, a hollow cylinder 9, closed at the bottom by a base, is turned or milled from a cylindrical stainless steel blank. The base forms a base plate 4, from the peripheral edge of which a thin-walled cylinder shell extends upwards. At the upper opening 12 of this hollow cylinder 9, the semi-finished product 1a has an undercut 5. The cylinder shell of the hollow cylinder 9 is divided into a plurality of webs by cuts 10, which run parallel to the cylinder's longitudinal center axis 11 and form an intersection point with this axis 11. These webs will later form the prongs 2 in the setting 1 to be produced. The cuts 10 are created in such a way that a straight cutting tool is guided such that it runs through the cylinder's longitudinal center axis 11 during cutting, and thus creates two cuts 10 in the hollow cylinder shell simultaneously on two diametrically opposite sides.The cuts 10 can have a maximum depth up to the inner surface of the base plate 4.

[0018] The cuts 10 can also, as in Fig. 1, end a little above the surface of the base plate 4.

[0019] According to the first preferred embodiment, twelve webs can thus be cut out of the cylinder material by six cutting processes, wherein the cutting tool, which runs through the cylinder longitudinal center axis 11, is rotated by 30° about the cylinder longitudinal center axis 11 after each step in order to produce twelve webs of equal width.

[0020] According to the first preferred embodiment, the cuts 10 have approximately half the width of the webs.

[0021] On the upper surface of the base plate 4, a conical recess 7 is machined in the center, which serves to position the culet 8 of the cut gemstone 3 to be set. This conical recess 7 is not absolutely necessary.

[0022] To produce the socket 1 according to the invention, this semi-finished product 1a is clamped in a tool and a suitably shaped conical tool head is inserted into the cylindrical semi-finished product 1a along the longitudinal center axis 11 through its upper opening 12 in such a way that the webs, which later form the prongs 2 in the socket 1, are each uniformly bent radially outwards at their upper ends.

[0023] The version 1 thus created has the Fig. 2 shown form.

[0024] The deformation of the webs caused by the conical tool head exceeds the elastic limit of the material of the socket 1 and represents a plastic, permanent deformation.

[0025] In the Fig. Version 1 shown in Figure 2 is, as in Fig. 3, the cut gemstone 3 is inserted. The Fig. 3 has a girdle 6, below which the lower part of the cut gemstone 3, which is provided with facets and tapers downwards to the cylinder's longitudinal central axis 11 of the setting 1, is located.

[0026] The prongs 2 of the Fig. 2 have hooks 5 at their upper free ends, which were created in the semi-finished product 1a by the undercut 5, the tips of which are located radially closest to the cylinder longitudinal center axis 11 lying on a circle, the diameter of which, after deformation, is slightly smaller than the diameter of the girdle 6.

[0027] Using a tool, the cut gemstone 3 is carefully pressed into the setting 1 from above. Due to the essentially conical shape of the cut gemstone 3 on its underside 3a, the setting 1 is slightly elastically expanded, allowing the gemstone 3 to slide into the setting 1. The prongs are expanded by an elastic, springy deformation. This means that when the girdle 6 is pressed under the hooks 5, the hooks spring back radially inward above the girdle 6 due to their elastic spring force and together grip the cut gemstone 3 in the setting 1 under mechanical tension.

[0028] This ensures that the cut gemstone 3 is securely held in the setting 1. Hand-cut and machine-cut gemstones 3 generally have large tolerances in diameter and height. As a result, conventional stone settings must be adjusted to each stone.

[0029] By fixing the cut gemstone 3 under tension, such adjustment is not necessary and gemstones with different dimensions can also be set securely.

[0030] The above description of a preferred embodiment of the present invention is for illustrative purposes only and is not to be construed as limiting. List of reference symbols 1 version 1a semi-finished product 2 prongs 3 cut gemstones 3a Underside of the cut gemstone 4 Base plate 5 hooks / undercut 6 girdle 7 conical depression 8 culets 9 hollow cylinders 10 cuts 11 Cylinder longitudinal center axis 12 upper opening

Claims

[1] Setting (1) for a cut gemstone (3) having a girdle (6), with a plurality of prongs (2) which jointly encompass the gemstone (3), the prongs (2) holding the gemstone (3) by a suitable choice of their material and shape through their inherent elastic spring force, characterized by in that the prongs (2) together form a plurality of webs and, starting from a base plate (4), the dimensions of which, when viewed from above onto the gemstone (3), are smaller than those of the gemstone (3), extend in a frustoconical widening envelope towards the gemstone (3) and hold the latter at their free ends under mechanical tension with spring force by means of hooks (5) directed towards the gemstone (3), the base plate (4) and the prongs (2) being formed in one piece, the spaces between the prongs (2) widening from the base plate (4) towards their free ends. [2] Version (1) according to claim 1, characterized by that the base plate (4) is circular in plan view and the prongs (2) extend radially obliquely upwards from its edge, where the hooks (5) grip the gemstone (3) together under tension. [3] Version (1) according to claim 2, characterized by that the material of the base plate (4) and the prongs (2) is stainless steel. [4] Semi-finished product (1a) of a socket (1) according to claim 2, characterized by that the prongs (2) extend from the edge of the round base plate (4) parallel to one another on a cylindrical envelope surface and have hooks (5) pointing radially inwards at their free ends. [5] Semi-finished product (1a) according to claim 4, characterized by that the round base plate (4) has a conical recess (7) in its center as a positioning aid for a culet (8) of a cut gemstone (3). [6] Semi-finished product (1a) according to claim 4 or 5, characterized bythat a plurality of prongs (2) are arranged at the same distance from one another and the distances between adjacent prongs (2) are half the width of the prongs (2). [7] Method for producing a semi-finished product (1a) according to one of claims 4 to 6, characterized by following steps: - producing a hollow cylinder (9) closed on one side with an undercut (5) at its open end by turning, milling and drilling, - Sawing out prongs (2) from the hollow cylinder shell by cuts (10) which run parallel to the cylinder longitudinal center axis (11) and extend from the open end of the hollow cylinder (9) to a maximum of the inner surface of the base plate (4) of the hollow cylinder (9) at the closed end. [8] Method for producing a part of a piece of jewellery or accessory, consisting of a cut gemstone (3) having a girdle (6), with a setting (1) according to one of claims 1 to 3, from a semi-finished product (1a) according to one of claims 4 to 6, comprising the following steps: - producing a semi-finished product (1a) using the method according to claim 7, - plastic, permanent deformation of the semi-finished product (1a) with a conical tool by centered insertion of the conical tool into the semi-finished product (1a) for permanent spreading of the prongs (2) such that the tips of the hooks (5) at the free ends of the prongs (2) lie on a circle whose diameter is smaller than the diameter of the cut gemstone (3) in the area of ​​the girdle (6), and - Pressing the cut gemstone (3) into the setting (1) with a tool by elastically spreading the ends of the hooks (5) through the underside of the cut gemstone (3a) against the elastic spring force of the prongs (2) until the restoring forces of the prongs (2) press the hooks (5) under tension onto the gemstone (3) in the area of ​​its girdle (6).

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