To examine variations in nacre color and thickness in oysters obtained from Tonga and Japan, a novel approach with a focus on their potential for mabé pearl production was used. Detailed analyses of color and microstructure revealed that the middle position of the right-valve nacre (position 1) primarily showed a reduction in yellow pigmentation. This was indicated by a decrease in the yellowness index (YI) and an increase in the whiteness index (WI). In contrast, the anterior and middle positions of the left-valve nacre (positions 2 and 3) consistently displayed a higher level of yellow pigmentation. A comparison of oysters from different geographical origin found that Tonga wild-caught oysters had significantly thicker nacre than Tonga culture-site oysters, suggesting the influence of probable genetic diversity and environmental factors on nacre formation. Notably, nacre at position 1 was generally thinner, while at positions 2 and 3 it was thicker, which would influence the resultant pearl quality and attributes. We demonstrate the significance of the nacre position on the valve for mabé pearl production: position 1 tended to produce white pearls with pronounced interference colors, whereas position 2 tended to yield gold pearls. Furthermore, our findings highlight the significant impact of the oysters' geographic origin on mabé pearl color and quality. This study emphasizes the importance of considering the position of shell nacre and the potential influences of the oysters' genetic origins and environmental factors on mabé pearl formation.

中文翻译：

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地理来源和贝壳位置对马贝珍珠贝珍珠贝珍珠质颜色和厚度的影响

为了检查从汤加和日本获得的牡蛎珍珠层颜色和厚度的变化，采用了一种新方法，重点关注其生产马贝珍珠的潜力。颜色和微观结构的详细分析表明，右瓣珍珠质的中间位置（位置1）主要表现为黄色色素沉着的减少。这通过黄度指数（YI）的降低和白度指数（WI）的增加来表明。相比之下，左瓣珍珠质的前部和中部位置（位置 2 和 3）始终显示出较高水平的黄色色素沉着。对不同地理来源的牡蛎进行比较发现，汤加野生捕获的牡蛎的珍珠层明显厚于汤加文化区牡蛎的珍珠层，这表明可能的遗传多样性和环境因素对珍珠层形成的影响。值得注意的是，位置 1 的珍珠质通常较薄，而位置 2 和位置 3 的珍珠质较厚，这会影响所得珍珠的质量和属性。我们证明了阀门上珍珠质位置对于马贝珍珠生产的重要性：位置 1 倾向于生产具有明显干涉色的白色珍珠，而位置 2 倾向于生产金色珍珠。此外，我们的研究结果强调了牡蛎的地理来源对马贝珍珠颜色和质量的重大影响。这项研究强调了考虑贝壳珍珠层的位置以及牡蛎遗传起源和环境因素对马贝珍珠形成的潜在影响的重要性。