1. Appearance: High-quality black tea usually presents a neat and tight shape, such as slender strips or tight balls. The leaves are uniform in color and glossy.

2. Tea color: High-quality black tea leaves will show a bright, vivid color, usually deep red or brownish red. This color reflects the natural floral and fruity aromas that are fully released during the fermentation and roasting process of the tea.

3. Aroma: High-quality black tea has a strong and long-lasting aroma, which can be floral, fruity, chocolatey and other diverse aromas. The aroma is mellow and fresh, and can be fully emitted when brewing.

4. Taste: High-quality black tea has a mellow, smooth and layered taste. Full flavor, long sweet aftertaste, giving people a comfortable and pleasant feeling. There will be no roughness or irritation.

5. Soup color: high-quality black tea usually has a clear, bright reddish-brown soup color. The color is bright, mellow and transparent.

6. Bubble resistance: High-quality black tea can withstand many brews, and the brewed tea broth still maintains its rich aroma and flavor, and will not quickly lose its tea characteristics.

It should be noted that each variety of black tea has its own unique characteristics and flavor, so the above characteristics are not applicable to all black tea. In addition, the quality of black tea may vary depending on factors such as origin, production process and storage conditions. For black tea lovers, tasting and comparing different varieties and origins of black tea is a way to better understand its characteristics and quality.