I lost a small stone from my setting. When I dropped it at a local jeweler to have it replaced they measured my center stone. The measurement was off. Certificate said 6.76 measured twice by two different people at 6.68. I asked for appraisal because ring is new and hadn't received second appraisal since purchase in another state. All measurements came back different (slightly). Jeweler said because of setting the stone was easy to measure. More importantly the color grade came back three levels lower and the clarity grade one level lower. Have bad feeling in stomach about stone... Seeking second appraisal. How common for this to all be different..?.