夜明珠的特点及其鉴别方法
夜明珠是一种稀有的宝石，古称“随珠”、“悬珠”、“垂棘”、“明月珠”等。通常情况下所说的夜明珠是指荧光石、夜光石。
它是地球大地内的一些发光物质经过了几千万年，由初的火山岩浆喷发，到后来的地质运动，集聚于矿石中而成，含有这些发光稀有元素的石头，经过加工，就是人们所说的夜明珠，常有黄绿、浅蓝、橙红等颜色，把荧光石放到白色荧光灯下照一照，它就会发出美丽的荧光，这种发光性明显的表现为昼弱夜强。此外，部分工艺品也利用萤石的特征制作一些冠以“夜明珠”名称的饰品。
“夜明珠”是在黑暗中，人眼能明视的，天然的、能自行发光的珠宝。
夜明珠是地球大地内的一些发光物质经过了几千万年，由初的火山岩浆喷发，到后来的地质运动，集聚于矿石中而成。夜明珠是世界几个古老文明中同时存在的一个自然、历史和文化之谜。 [1] 据史籍记，史前炎帝、神农时就已发现过夜明珠，如神农氏有石球号称“夜矿”。春秋战国时代，如“悬黎”和“垂棘之璧”，价值连城，可比和氏璧。当时只有大官家陶朱公（范蠡）和猗顿（战国时大商人）二人买得起。晋国曾以“垂棘之璧”为诱饵“假首与虞以代编”。楚、秦、魏等国的大夫曾借夜明珠寓意哲理，讨论国家大事。秦始皇殉葬夜明珠，在陵墓中“以代膏烛”。汉光武皇后的弟弟郭况“悬明珠与四垂，昼视之如星，夜望之如月”以炫耀其富有。武则天赐与玄宗玉龙于夜明珠，玄宗又回子（世宗）一清珠，光照一室。唐有车时，一颗名为“水珠”的夜明珠，售价亿万。宋元明时，尤喜夜明珠，其中成吉思汗夜明珠，在台湾曾被偷盗，后被破案，物归原主。元明曾派官员到斯里兰卡买到红宝石夜明珠和石榴石夜明珠。明代内阁曾有数块祖母绿夜明珠，夜色有光明如烛。
按材质分
“夜明珠”按照基体材质的不同可分两大类。
夜明珠
1．动植物性“夜明珠”：动物界有夜光者如的萤火虫，人人皆知。唐代苏颚《杜阳杂编》记唐代宗宝历元年，南昌国献“夜明犀”。植物界有夜光者很多，如《本草纲目》记载灵芝中的“木威喜芝”、“参成芝”、“七明九光芝”都发荧光。
2．矿物宝石类夜明珠：从固体物理学角度矿物性“夜明珠”的基体材料都是无机盐类晶体中的激活晶态磷光体。
所谓激活晶态磷光体是指由于晶体晶格点阵畸变而获得“发光”本领的晶体，而这种畸变，又多半是由于基质内含某些重金属杂质（激活剂）所引起的。例如ZnS中含少量的Cu就能发出黄绿色磷光，此ZnS称为基质，Cu称为激活剂。
按磷光体
由于激活晶态磷光体中激活剂的不同可将激活晶态磷光体也就是“夜明珠”分两类：
稀土夜明珠
1、发光的夜明珠：不需要借助任何外界能量进行激发，而是靠自身含有激活剂，如14C．3H． 147Pm．226Ra．232Th．等放射性同位素，能自身激发而发光的。
2、长余辉蓄光型夜明珠：磷光体中的激活剂没有放射性，靠外界的日光、紫外线等光源激发后才能发光的。 今常用的磷光体不下百种，它们的化学成分除了碱金属卤化物外，都是二价金属（Ca、Sr、Ba、Cd、Mg、Zn）的化合物——硫化物，硒化物，碲化物，硅酸盐，铝酸盐，钨酸盐，磷酸盐和卤素磷酸盐类。
其中，硅酸盐和铝酸盐类稀土蓄光性夜明珠由于采用新型稀土发光材料为主要原料，无害无辐射，环保健康，已经得到较多应用，比如人造硼铝酸锶夜明珠、稀土夜光弹力球（寻龙珠）等。
天然夜明珠是极稀有和的，我们鉴定它的真伪，除了用宝玉石方面的检测仪器科学进行鉴别外，还可以根据它具备的许多特性进行识别。
天然
（1）须经光照15分钟
世界上大夜明珠
，能在数十个小时内连续发光的浅灰色萤石。
（2） 具有磷光现象，既能产生夜明珠准效应者。
（3）颜色美丽，半透明，无须任何光照，即主动发光，并且发光能量较大。
（4） 一定要把萤石的萤光和磷光区分开来，磷光现象是在外加光源作用，去掉后还能保持一定的发光时间。
（5）观察它的发光长度、均匀度，及半衰期，余辉长短。
人造
（1）在自身不发光的萤石裂隙中填充萤光粉，仅局部或线条状发光。
（2） 发光部位通过光照后，时间短瞬即逝。
（3）填充发光物，破绽楚楚，有明显的痕迹，肉眼观看，比较容易识破。
由于夜明珠价值较高，在鉴定真伪时，要持严肃、认真的态度，应有国家宝玉石检测机构出具鉴定证书作依据。
The night pearl is a rare gem. It is known as "following beads", "hanging beads", "hanging spines", "bright moon beads" and so on. Generally speaking, the luminous pearl refers to phosphor and noctilucent.
It is the earth earth a few light-emitting materials after tens of millions of years, from the initial eruption of volcanic magma, to the later geological movement, gathered in the ore, containing these rare elements of luminescence stone, after processing, it is known as the night pearl, often yellow green, light blue, orange red and other colors, the fluorescent stone Put it under a white fluorescent lamp, and it will give out beautiful fluorescence. This luminescence is obviously manifested by weak day and weak night. In addition, some handicrafts also make use of the characteristics of fluorite to make some ornaments with the name of "night pearl".
"Night pearl" is a natural, self luminous jewellery in the dark, which the human eye can see.
The night pearl is a few tens of millions of years in the earth's earth. It was erupted from the original volcanic magma to the later geological movement and gathered in the ore. The night pearl is a natural, historical and cultural riddle that exists in several outstanding ancient civilizations of the world. [1] according to historical records, prehistoric Emperor Yan and Shen Nong have already found bright pearl at night, such as Shen Nong's king of stone balls, known as "night mines". In the spring and Autumn period and the Warring States period, such as "hanging Li" and "hanging spine", they were worth a lot of money. At that time, only two officials of the grand officials, Tao Zhu Gong (Fan Li) and Yi ton (great merchants in Warring States period), could afford it. In Jin Dynasty, bait "false head and Yu" were used as bait. Doctors in Chu, Qin, Wei and other countries used the night pearl to symbolically and philosophically discuss national affairs. Qin Shihuang died in the tomb of the Pearl, in the mausoleum "to replace the cream." Kuang Kuang, brother of the queen of Han Guang Wu, "hangs pearls and four hangs, looks like stars in the daytime, and watches the moon like the moon" to show off its wealth. Wu Zetianci and Xuanzong ERON are in the Pearl of the night, Xuanzong and Hui Zi (shzong), a pearl of the Qing Dynasty. When Tang had a car, a night pearl called "water droplet" was priced at hundreds of millions of dollars. During the Song, Yuan and Ming Dynasties, the royal family especially liked the night pearl, of which Genghis Khan night Pearl was stolen in Taiwan, and was later cracked and returned to its original owner. Yuan Ming sent officials to buy Ruby pearl and garnet night pearl in Sri Lanka. There were several emerald night pearls in the Ming Dynasty cabinet, and the night was bright as candles.
According to material
"Night pearl" can be divided into two main categories according to the material quality of the matrix.
Night-luminescent Pearl
1. the "night pearl" of animals and plants: there are nocturnal people in the animal kingdom, such as the famous fireflies. In the Tang Dynasty, the "duyang" was written in the first year of emperor Zong Baoli in Nanchang. There are many luminous plants, such as "Ganoderma lucidum" recorded in the "Compendium of Materia Medica" Ganoderma lucidum, "Ganoderma lucidum", "Shen Chengzhi", "Qi Ming Jiu Guangzhi" are all fluorescent.
2. Mineral gemstone nocturnal pearls: From the point of view of solid state physics, the matrix materials of mineral "nocturnal pearls" are all activated crystalline phosphors in inorganic salt crystals.
The so-called activated crystalline phosphors refer to the crystals of "luminescent" power due to lattice lattice distortion, which are mostly caused by some heavy metal impurities (activators) in the matrix. For example, a small amount of Cu in ZnS can emit yellow green phosphorescence. This ZnS is called matrix and Cu is called activator.
Phosphor
Because of the difference of activators in activated crystalline phosphors, the activated crystalline phosphors, the "luminous pearl", can be classified into two categories.
Rare-earth night Pearl
1, perpetual luminous pearl: do not need to use any external energy to stimulate, but by its own activator, such as 14C.3H.147Pm.226Ra.232Th., such as radioactive isotopes, can be excited and luminescent.
2. Long afterglow light-storing nocturnal pearl: the activator in phosphor body has no radioactivity, it must be excited by outside sunlight, ultraviolet light and other light sources before luminescence. No more than 100 kinds of phosphors are commonly used today. Their chemical constituents are compounds of two valence metals (Ca, Sr, Ba, Cd, Mg, Zn) - sulphides, selenides, tellurides, silicates, aluminates, tungstate, phosphates and halogen phosphate.
Among them, silicates and aluminate rare earth light storage night pearls have been used as the main raw materials for the use of new rare earth luminescent materials, innoxious and harmless and no radiation, environmental health, such as the strontium borate night pearl, the rare earth luminous ball (Xun Longzhu) and so on.
The natural night pearl is extremely rare and rare. We can identify its authenticity, in addition to the identification of the instrument science of gemstone, and it can be identified according to its many characteristics.
natural
(1) it must be illuminated for 15 minutes
The biggest night pearl in the world
Light gray fluorite that can continuously shine in dozens of hours.
(2) phosphorescence can produce the quasi effect of night pearl.
(3) the color is beautiful, translucent, without any light, that is, permanent active lighting, and the luminous energy is larger.
(4) Fluorescence and phosphorescence of fluorite must be distinguished, phosphorescence phenomenon is in the role of external light source, after removal can maintain a certain luminous time.
(5) to observe its luminous length, uniformity, half-life and duration.
artificial
(1) filling fluorite powder in the fissure which does not luminate itself, emitting only local or linear luminescence.
(2) the luminous parts are transient after passing through light.
(3) filled with luminescent materials, they are very clear and have obvious marks. They are easy to see through naked eyes.
Because pure natural night pearl is of high value, it is true and false.
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