Cut (gems)
When sanding is referred to in the gemology generated by grinding type and form of gemstones to enhance their shine and highlight the stone inherent optical effects.
The choice of the cut and the quality of execution are in addition to color and purity essential for the subsequent value of the gemstone. Because of this necessary experience, among other things with the different properties of the materials used as gems quality cuts for commercial use are usually performed by specially trained gem cutters.
- 2.1 polygons
- 2.2 Circles, ellipses and egg shapes
- 2.3 Three-dimensional shapes
- 2.4 Other forms of ground
Schliffart
When grinding gemstones distinguish between three different types of grinding, which refer to the respective characteristics of the stone consideration.
Straight cut
To obtain smooth cut a smooth, edgeless to a possible girdle surface is generated. It is preferably used in opaque to translucent gemstones. These often show a lively play of colors such as grains and stains. The smooth cut is also the only form that brings special optical effects such as adularescence, asterism and chatoyancy and typical of these stones, silky shine to full fruition.
The most famous smooth cut is the cabochon, but also able stones, ball and tumbled stones ( stones Baroque ) belong to the smooth cuts.
Different crystals in spherical ground
Jasper in egg shape
Rose quartz heart-shaped
Chrysocolla Malachite stone aggregate as a drum
To a cameo processed sardonyx stone location ( fight scene Shapur I against Valerian )
Facet cut
The facet cut is known about since the 15th century and consists of a variety of small, smooth polished surfaces, the facets. It is mostly used in transparent stones, as they are able to reflect incoming light to break and often multicolored split ( dispersion). This phenomenon, the fire of a stone is, in particular, reinforced by the modern brilliant full-cut, which was developed in 1910. The optimum light refraction comes here by well-defined angular relationships between the 58, arranged according to a certain scheme, facets about. The brilliant cut was preceded by a continuous development: initially only the natural octahedral faces of diamonds were polished before started gradually with the creation of additional facets.
Most Faceted surface can be divided into two basic types, the already mentioned brilliant cut for more rounded and the step cut with more angular shapes. Added to this are as special forms of rose cut, the oval and the pendeloque for round as well as the emerald cut and the scissors cut for square.
Rose cut
Oval cut
Pendeloque
Step cut
Emerald cut
Scissors cut
Mixed cut
When mixed cut finally smooth and facet cut are combined. Depending on the desired effect or fashionable taste is doing the top and bottom of the cabochon and designed as bevelled edge ( "Buff Top" ) or chosen two different facets cuts for the top and bottom. In some cases, two types of grinding to be united on one side.
For example, part of the " Ceylon " processing ( also Ceylon ) to the mixed sections, in which the upper part of the scissors cut and the lower part is executed step-cut. In contrast, the upper part of the step cut and the lower part is performed in the scissors cut the " Indian touch".
Cut form
In the definition of cut of the slider refers to the geometric shape of the later gemstone. These are derived from the classic geometric shapes such as the circle and the square. Differences are the sections according to the following basic types:
Polygons
- Triangle ( triangle, Trillant ): Triangular basic form in the execution brilliant cut with table, six quadrilateral and 18 triangular facets. The execution step-cut is possible. "Coat of arms " or " sign": Fantasy cuts in the form of a coat of arms or blazon step-cut.
- Square ( Carré ), brilliant and step cut possible
- " Cardinal cut " star cut ( double star ) with square cross section
- Rectangular ( baguette ) " Oblong " Elongated rectangular shape with rounded corners.
- " Ceylon touches " and " Indian touch" mixed- cut with rounded corners
- " French Cut" ( also Frenchcut ): Special shape with a square cross-section and panel square and 8 triangular facets on the top. The lower part is optionally performed in the stair or brilliant cut.
- " Epaulette ": pentagon variant, which is modeled on the French shoulder piece in the mold.
- " Emerald cut " (also octagonal section): Octagonal meeting ground
- "Star Bright ": Fantasy cut in the shape of an eight -pointed star
Elbait square cut
Green Tourmaline emerald -cut
Ametrine in scissor cut
Zirconia as eight -pointed "Star Bright "
Circles, ellipses and egg shapes
- Simple round cut with table and several concentric stairs in 16 segments.
- Brilliant cut (even full diamond or highlight brilliant ) cut with a circular girdle, at least 32 facets plus panel in the upper part, at least 24 facets plus any culet in the lower part. " Octagon " (also octagonal cut or Simplified brilliant cut ): Special diamond cut with blackboard, 8 upper and 8 lower facets
- Double diamond
- "English square cut " (also English Double tip or English Square -cut diamond ): Early form of brilliant cut with an octagonal table and 16 facets on the top and 12 facets on the lower part
- " Star-cut " brilliant-cut in which the facets of the girdle extend to the center to form a star-shaped pattern. "English star cut ": brilliant cut with 16 facets on the top and 12 facets on the lower part
- " Sunray " (also radial cut ): flap-grinding evenly with fan-shaped facets
- Rose-cut (also Simple Rose Dutch Rose or Rose Amsterdam ): Cut with a flat bottom and 24 triangular facets on the domed top. " Antwerp Rose" ( Brabant Rose): old cut from the 16th century with 12 trapezoidal and triangular facets.
- Double Rose: 32 triangular facets on the curved surface.
- Derived as special shapes or fantasy grindings of them include the " Recoupé Rose ", the " Jubilee Cut" with 80 rosettes arranged facets forming a peak towards the upper part, and the " Needle - Brillant".
- "Oval": Elliptical cut as brilliant cut, with central panel, 8 square and 24 triangular facets on the top " Navette " or " Marquise ": Ellipse, run their transitions in large diameter pointed.
Prehnite in " Petal - Cut"
Citrin Oval Cut
Diopside Navette
Dresden Green Diamond in pendeloque cut ( copy)
Three-dimensional shapes
- "Ball ": Spherical Brilliant Cut
- " Olive": olive -shaped brilliant cut
- " Briolett ": Pear-shaped facet cut with triangular, diamond-shaped or trapezoidal facets " Grapefruit ": arranged Pear-shaped brilliant cut with tapered, elongated facets and apex truncated.
Great Star of Africa in broad drop or pear shape
Garnet in the spherical ground
More cut shapes
- " Antique cut ": Square or rectangular cut shape brilliant or step cut with rounded corners
- " Balloon touch": facet cut with convex facets
- " Barion -cut ": Rectangular or octagonal shape with step cut on the top and conical faceting on the bottom
- ' Context Cut ": Modern, octahedral sanding with a flatter upper part
- "Flower Cuts": Modern diamond cuts in the forms " Zinnia " ( Zinnia ), " Marigold " ( Marigold ), "Fire Rose" ( Fire Rose), "Sunflower " (Sunflower) and " Dahlia" (Dahlia ).
- "Gabrielle - Cuts": Special patented by Gabi Tolkowsky cut shapes
- "Heart " (also touches heart ): heart -shaped brilliant-cut
- ' Lens cut ' step cut, in which the facets of the upper and lower part extending in one direction.
- " Princess cut " (Princess cut): mixed cut in touch with Cardinal on the top and flap-grinding on the lower part.
- "Radiant ": Mixed step cut with diamond cut on the upper part, brilliant cut on the lower part and a total of 70 facets.
- " Panel cut ", also sealed, flat, plate or ring stone finish: Simple bevelled edge, in which the panel on the top and usually on the bottom is the dominant facet.
Diamond in " princess cut " (Princess cut)
Turquoise and argillites ( fine-grained sedimentary rock, orange) in the panel cut