Divided gems are also called combined gems. Gemstones made of the same or different kinds of rough stones are cut into top and bottom respectively, and then bonded or combined to form a bottom pad. It is listed as "artificial products" in the national standard of jewelry and jade. There are three types: double layer, triple layer and bottom support (pad).
Structural types of assembled gems
All kinds of split stones, whether two-layer stones, three-layer stones or substrate stones, are composed of two or more identical or different materials layered to form an overall appearance, and metal brackets (precious metals or base metals) are embedded to cover the interlayer bonding joints.
I. Morphology of Structural Layer
1, planar shape
The structural layer of faceted mosaic is flat, and the layers that make up the mosaic are horizontally integrated.
2. Surface shape
Whether it is round, oval or hollow oval, all structural layers of arc-shaped split stones are arc-shaped thin layers, and all layers are in arc-shaped parallel contact. The cross-sectional shape of this cambered mosaic stone has several forms, such as single convex, double convex, concave-convex and concave.
Second, the hierarchical structure layer
1, double-layer structure
(1) Colorless cemented double-layer structure: the split stone is composed of two layers of materials, the top layer is mostly transparent or translucent natural gems or man-made products with good durability, the bottom layer is made of inferior and cheap materials, and the upper and lower layers are bonded with colorless adhesive. This kind of splitting stone is actually composed of three materials.
(2) Color bonded double-layer structure: the bottom or pavilion of transparent or translucent gemstone is coated with pigment or color film, which consists of two materials.
2. Multilayer structure
Multi-layer structure refers to a gem structure made of three kinds of gem materials or more than three different materials.
(1) colorless cemented three-layer structure: three gem materials of the same variety or different varieties are bonded together with colorless glue. This structure is actually composed of five layers of materials.
(2) Color bonding three-layer structure: two kinds of gem materials of the same variety or different varieties are bonded into a whole with color adhesive. This mosaic has only three layers.
Identification method
Taking the identification of spliced garnet as an example, the identification method is as follows:
1. With naked eyes, the spliced garnet looks like a ruby, and the glass has a strong luster, vaguely feeling that the pavilion has a dim luster. Depending on the refractive index of the material, glass is relatively dark, while garnet is relatively bright.
2. Carefully distinguish the pavilion with a microscope and see the stitching marks. There are obvious differences between the two materials in hardness and luster. Some splicing materials have similar hardness, and the splicing line can be found by careful identification.
3. When the dividing line extends to the surface, dispersed bubbles and flow vortex structures can be found. This is because it is difficult to remove all bubbles in the stitching process. They are distributed along the bonding plane, and some even look like fingerprints.
4. It is easier to distinguish spliced garnet from emerald. Generally, the top layer is almandine and the bottom layer is glass. The identification method is to illuminate the pavilion with a point light source under a microscope, and red circle marks appear, that is, the "red circle effect". Similarly, bubble inclusions will also appear in the splicing layer.