2020年新加坡拍卖精品推荐

欧泊是世上最美丽和最珍贵的宝石之一，世界上95%的欧泊出产在澳大利亚。欧泊的化学成分组成是SiO2˙nH2O（二氧化硅水合物）。根据欧泊胚体色调的显示，它可以分为无色、白色、浅灰、深灰一直到黑色。不同于其它宝石的是，欧泊所具有迷人的色彩是根据随机的“变色游戏”来呈现光谱中各种色彩的。

欧泊是凝胶状或液体的硅石留入地层裂缝和洞穴中沉积凝固成无定形的非晶体宝石矿，其中也包含动植物残留物，例如树木、甲壳和骨头等。在高等级5欧泊中的含水率可高达到10%。

在欧泊形成过程中，二氧化硅溶液犹如岩浆流入内陆地层的缝隙和空矿地带沉积。沉积作用发生在距地表约四十米深处,大约每五百万年沉积物会加一厘米的厚度。这个阶段以后的一、二百万年期间随着气候变化沉积物开始慢慢凝固。欧泊是没有黏结在其他沉积物上、又过了相当长的时间才坚硬的部分。

我们通常将天然欧泊分为两大类：“普莱修斯欧泊”和“普通欧泊”。普莱修斯欧泊色泽明亮、能呈现出充分的变色效应，比较稀有和珍贵。色泽暗淡、不能呈现变色效应的称为普通欧泊，普通欧泊在世界各地都有发现和少量出产。

在欧泊矿区开采出来的欧泊中95%都是普通欧泊，通常只有白的、灰的或者黑的一种颜色。它们只适合做“德博莱欧泊”和“翠博莱欧泊”的背景衬石。剩下的5%中是有一些色彩的等级欧泊，不过其中的95%也只是普通的等级。也就是说，开采量中只有大约0.25%才可以称做真正有价值的欧泊。

普莱修斯欧泊被定义为会变色游戏的硅蛋白石。术语“变色游戏”是专门用来形容珍贵欧泊美丽绝伦之变幻色彩的。澳大利亚出产的欧泊有时也被称为“沉积的宝石”是因为它主要形成和出产于中生代大自流井盆地中的沉积岩中。普莱修斯欧泊通常含有6-10%的水分，同时它所包含的小硅粒被排布成有规则的图案。比重主要根据含水率不同在1.9-2.3之间。

硅石凝结过程中，水分逐渐减少，凝胶形成球体状，球状体自然附着小粒的硅石，这些无定型硅粒的尺寸在1500埃到3500埃（1埃等于一亿分之一厘米）。这些球粒虽然很小，但是布满了欧泊内部，十分规则的排列着。由于它们是圆的球体，从结构上来说有很小的空隙（好像很多大理石圆球被放置在容器中后出它们之间的空隙），这些空隙是三维排列的。欧泊的色彩正是由于这些规则排列的空隙通过光学衍射作用分解白光产生的。当硅粒比较大的时候，空隙相对也会比较大，红色或橙色的衍射光线就会出现。如果硅粒比较小，同样空隙就会比较小，蓝紫色的光谱就通过衍射作用被分解出来。其中的色彩过度就如同彩虹变化一般，光线衍射作用最强的是空隙尺寸最大的，因此红色变彩的欧泊表面往往很明亮，而蓝色变彩则相对比较暗淡。

总之，普莱休斯欧泊的色彩变化来自于规则排列的硅粒和之间空隙对白光的衍射作用。硅粒的直径决定了欧泊颜色的分布范围，小的硅粒会使欧泊产生通常的蓝紫色，反之会产生珍贵的红色。每一枚欧泊根据自身品质都具有不同的价值，主要的决定因素是：胚体色调、变色游戏、颜色、明亮度；图案、尺寸和形状等。

Opal is one of the most beautiful and precious gems in the world. 95% of the world's opals are produced in Australia. The chemical composition of Opal is SiO2˙nH2O (silica hydrate). According to the hue of the opal embryo body, it can be divided into colorless, white, light gray, dark gray and black. Unlike other gems, Opal's fascinating colors are based on random "color-changing games" to present various colors in the spectrum.

Opal is a gel-like or liquid silica that is left in formation fissures and caves to deposit and solidify into an amorphous amorphous gemstone mine, which also contains animal and plant residues, such as trees, carapace, and bones. The water content in high-grade 5 opals can be as high as 10%.

During the formation of Opal, the silica solution was like magma flowing into the crevices of the inland layer and deposited in the empty mine zone. Sedimentation takes place at a depth of about 40 meters from the surface, and the sediment will add one centimeter in thickness every five million years. During the next one or two million years after this period, the sediment began to slowly solidify with climate change. Opal is a hard part that does not stick to other sediments and takes a long time.

We usually divide natural opal into two categories: "Plausius Opal" and "General Opal". Pleasant Opal is bright in color and can exhibit sufficient color change effect, which is relatively rare and precious. The dull color, which can not show the effect of discoloration, is called ordinary opal. Ordinary opal is found all over the world and produced in small quantities.

95% of the opals mined in the opal mining area are ordinary opals, usually only white, gray or black. They are only suitable for the background lining of "De Bole Opal" and "Tribble Opal". Of the remaining 5%, there are some grades of opal, but 95% of them are only ordinary grades. In other words, only about 0.25% of the mining volume can be called a truly valuable opal.

Pleasant Opal is defined as a silicon opal that can change color. The term "color-changing game" is specifically used to describe the beautiful and changing colors of precious opal. The Opal produced in Australia is sometimes referred to as "deposited gemstone" because it is mainly formed and produced in the sedimentary rocks in the Mesozoic large artesian well basin. Plausius Opal usually contains 6-10% moisture, and the small silicon particles it contains are arranged in a regular pattern. The specific gravity is mainly between 1.9-2.3 according to the moisture content.

During the condensation of silica, the water gradually decreases, and the gel forms a sphere. The spheres naturally adhere to small particles of silica. The size of these amorphous silicon particles is 1500 to 3500 Angstroms (1 Angstrom is equal to one hundred millionth of a centimeter). Although these pellets are small, they are filled with opal and arranged in a very regular manner. Because they are round spheres, there are very small voids in structure (it seems that many marble round balls are placed in the container to leave the gap between them). These voids are arranged in three dimensions. Opal's color is caused by the regular diffraction of these white light through optical diffraction. When the silicon particles are relatively large, the gap will be relatively large, and red or orange diffracted light will appear. If the silicon particles are smaller, the gaps will be smaller, and the blue-violet spectrum will be decomposed by diffraction. The excessive color is like a rainbow change. The strongest light diffraction effect is the largest gap size. Therefore, the red-colored opal surface is often very bright, while the blue-colored change is relatively dim.

In short, the color change of Plessius Opal comes from the diffraction effect of regularly arranged silicon particles and the gaps between them on white light. The diameter of the silicon particles determines the distribution range of the opal color. Small silicon particles will cause the opal to produce the usual blue-violet, otherwise it will produce a precious red. Each opal has different values according to its own quality. The main determinants are: hue of embryo body, color change game, color, brightness; pattern, size and shape.

2020年5月28日