This rough stone appears as a warm, brownish-yellow color under natural light, but reveals a deep and captivating blue fluorescence when backlit, a unique optical effect of blue amber. The stone retains its complete natural outer layer with natural texture, and the exposed window clearly reveals the pure, unblemished interior, free of obvious cracks or impurities. When backlit, the interior exhibits a uniform, high-intensity blue fluorescence, a characteristic of high-quality blue amber.