Precision jewel Parts

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         2021/05/07 Principal of Cylinder Phonograph, Sound Groove and Stylus Tip
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          History of Stylus Tip and Gramophone Record
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         2021/05/06 What are Diamonds？: Synthesis of Diamonds
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          What are Diamonds?
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         2021/04/26 Crystal of Jewel
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          Color of Jewel
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          Cut of Jewel
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          Cleavage of Jewel
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         2021/04/20 Novel Diamond Semiconductors Operate at Highest Power Ever
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         2021/04/14 Production of Sapphire
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          What is the Sapphire?