Tian Huang, as the name suggests, refers to a yellow-colored stone found in Shoushan Tiankeng. While the overall production of Tian Huang is relatively high and many old yellow stones and seals can be found in private collections, it's important to note that the quality varies greatly, and so does its value. Not all pieces are suitable for collection or high-value investment. Only a few of them possess exceptional characteristics, with every aspect being perfect and flawless. To truly appreciate a top-grade Tian Huang stone or seal, several key factors should be considered: Color: The most obvious feature of Tian Huang is its "yellow" color, which is not only the defining trait but also holds cultural significance. In Chinese tradition, yellow represents royalty and power, making it a symbol of prestige. A top-grade Tian Huang should have a bright, vivid yellow that is eye-catching and radiant, like golden splendor. If there are outer layers such as "silver bag gold," "golden package silver," or "crow skin," they should contrast sharply with the yellow, showing a clear distinction between yellow and white, or yellow and black. Stones with dull, murky, or mottled colors, even if the texture is good, cannot be considered top-grade. Quality: The quality of Tian Huang is typically judged by the "six de" standards—fine, clean, warm, moist, condensed, and greasy. A top-grade piece should be smooth, transparent, pure, and delicate, with a lustrous sheen. When held in your hand, it should feel soft and tender, like an infant’s skin. Even without polishing, it should remain moist and never feel dry. Additionally, the texture should be beautiful, with minimal and light lines. If there's a cortex layer, it should be thin and fine. Shape: While square or tall shapes are generally preferred in stones or seals, Tian Huang naturally comes in oval forms. Most people find it hard to reshape into a square, so when evaluating, the shape should be as full and round as possible, with balanced proportions in length, width, and thickness. Stones that are short, small, thick, angular, or irregular in shape are not worth a high price, regardless of their weight. In terms of form, smaller and elegant is better than large and ordinary. Carving: Lastly, a top-grade Tian Huang must be well-carved. As the saying goes, "Jade is not complete without carving," and the same applies to Tian Huang. Even the finest stone is just a raw block without proper craftsmanship. A great seal requires skilled artistry, with attention to detail, symmetry, and aesthetic appeal. Without this, it remains just a fine stone, not a true work of art.
Precision Optical Flats are ideal for a variety of applications including interferometry, imaging systems, laser applications, optical path folding, and autocollimation. These mirrors are available in a variety of coating and substrate options, along with surface flatness options of λ/10 and λ/20. Fused Silica, is optically clear and features excellent resistance to abrasion and high durability, making it the best choice for applications in harsh environments.
Silicon features a Knoop Hardness of 1150 and low density, making it tougher than germanium substrates and suitable for weight-sensitive applications, respectively. Diamond-Like Carbon (DLC) Coated Silicon Windows are engineered for 3 to 5µm, making them ideal for infrared defense applications such as thermal imaging. Silicon Mirrors,Infrared Si Lens,Infrared Silicon Wafers,Silicon Plates China Star Optics Technology Co.,Ltd. , https://www.csoptlens.com
Diamond-Like Carbon (DLC) Coated Silicon Windows provide anti-reflection coating on one surface and a specially designed DLC coating on the other surface, making these windows highly durable and ideal for harsh environments.
Silicon windows,Silicon Lens and Silicon Optical Mirrors specifications:
Standard precision of Silicon lens and optical mirrors
High-precision of Silicon lens and optical mirrors
Dimension Tolerance
φ5-250mm+0/-0.2
φ3-350mm+0/-0.2
Thickness Tolerance
1-50mm+/-0.1
1-50mm
Centration
3 arc minute
1 arc minute
Surface Quality
60/40
20/10
Power(fringe@633nm)
N<λ/2@633nm(in 25mm)
N<λ/10@633nm(in 25mm)
Clear Aperture
>90%
>95%
Chamfer
Protected <0.5mmx45deg
Protected <0.5mmx45deg
Tian Huang Appreciation Method