The pearl begins when the mollusk secretes a lustrous substance , called nacre , that coats the irritant and protects the soft internal surface of the mollusk 得天独厚的自然条件，配合来自珍珠养殖业的翘楚日本的高超技术，是澳洲南洋珍珠高品质的保证。
5 a round to near - round ; moderate / low luster ; thin nacre ( less than . 2 of total nacre ) ; 60 - 70 % inclusion free surface ; good to moderate matching 5 a圆到接近圆的程度，中/低的光泽，簿的珠层（小于0 . 2的珠层含量） ， 60 % - 70 %的表皮光洁度，良好到中等的匹配。
A tiny bead is implanted in an oyster , so that it is gradually coated in layers of a beautiful , pearlescent substance called nacre which build up to create a lustrous pearl 尤其是在近两年的日本及欧美，珍珠饰品含蓄内敛的气质吸引了不少知性女子，成为时尚饰品的一大主流。
7 commercial quality near - round to off - round ; moderate / low luster ; thin nacre ( less than . 2 of total nacre ) ; moderate to heavy inclusions ; good to moderate matching 7经济级的质量，接近圆到不圆，中/低光泽，簿的珠层（小于0 . 2的珠层含量） ，中等到大量的瑕疵，良好到中等的匹配。
As an oyster creates a pearl , the layers of nacre do not always adhere smoothly . sometimes spots and bubbles can appear in the layering process 由于光的反射，使珍珠看起来明亮有光泽由于光线的透射，使珍珠看起来晶莹剔透由于折射，光线会生产干涉现象，从而产生了变幻不定的色彩。
2 aa + perfect round ; excellent luster ; thick nacre ( . 5 of total nacre or better ) ; 90 - 95 % inclusion free surface ; excellent matching ; top 5 % of a pearl farm ' s harvest 圆度极高，极好的光泽，厚的珠层（ 0 . 5或以上的珠层含量） ， 90 - 95 %的表皮光洁度，极好的匹配，珠农收成中最好的5 %部份。
1 aaa perfect round ; excellent luster ; thick nacre ( . 7 of total nacre or better ) ; 95 % inclusion free surface or better ; excellent matching ; top 1 % of a pearl farm ' s harvest 1 aaa圆度极高，极好的光泽，厚的珠层（ 0 . 7或以上的珠层含量） ， 95 %的表皮光洁度或更高，极好的匹配，珠农收成中最好的1 %部份。
The quality of pearls is judged by the orient , which is the soft iridescence caused by the refraction of light by the layers of nacre , and lustre , the reflectivity and shine of the surface 珍珠的价值主要由它的光泽颜色大小有无表面的缺陷和形状来决定的，其中光泽为最重要的因素。其特有的光泽是光
2 ) the carotenoids successfully probed in nacre by in situ resonance raman spectra , are considered one of the most important factors responsible for the coloration of nacre and pearl 2 )采用共振拉曼光谱首次成功地原位探测到三角帆蚌及马氏珍珠贝珍珠层中类胡萝卜素的存在，并提出类胡萝卜素是珍珠层致色的重要原因之一。
3 aa very round ( less than 5 % gradation ) ; good luster , good nacre ( . 35 of total nacre or better ) ; 80 - 90 % inclusion free surface ; good / excellent matching ; top 20 % of a pearl farm ' s harvest 3 aa非常圆（少于5 %的那部份的等级） ，良好的光泽，良好的珠层（ 0 . 35或以上的珠层含量） ， 80 % - 90 %的表皮光洁度，好/极好的匹配，珠农收成中最好的20 %部份。
