Orthodontics
发表于 2025-3-26 21:26:32
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抗体
发表于 2025-3-27 04:06:09
Colour,nterference or dispersion, all of which give areas of all the spectrum colours. A number of optical mechanisms can give rise to the colour of a gemstone, including dispersion, interference, diffraction and scattering (which may give other optical phenomena too).
Petechiae
发表于 2025-3-27 09:00:01
Synthetic and imitation Stones,ely applied over the years. With the development of Trades Description Acts, the importance of this question is now more than merely academic but I must leave it to readers to apply their terminology sensibly.
Brain-Waves
发表于 2025-3-27 10:03:20
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清洗
发表于 2025-3-27 17:33:24
Descriptive section: inorganic materials,rder to avoid overloading the text with figures which have no more than academic significance, I have not provided items such as dispersion for more than a few species in which this property is important.
马笼头
发表于 2025-3-27 21:36:43
Formation and occurrence of gemstones,ble: diamond for example is very rare indeed compared to salt or quartz, but not compared to ruby, the particular conditions needed for the formation of which are encountered hardly at all. Few entirely new gem mineral species have been found in the last few years; tanzanite, appearing on the gem ma
sultry
发表于 2025-3-27 23:44:49
The nature of gemstones,in 1912 likened the relationship of the particles to a solar system with a central nucleus surrounded by circling electrons at different distances or energy levels from the nucleus. The nucleus, except in hydrogen atoms, is composed of protons with a positive electrical charge and neutrons which are
熟练
发表于 2025-3-28 05:16:58
Gem testing,the table is not quantitative but will indicate when a mineral can be scratched by a sharp edge or point of others above it in the scale. Diamond is placed at 10 and the test is diagnostic only for this species.
Debrief
发表于 2025-3-28 08:14:47
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CLOT
发表于 2025-3-28 13:31:55
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