Split Cassia is primarily graded based on its oil content, thickness, and cleanliness. High-quality Split Cassia should have a reddish-brown color and a strong, pungent aroma, indicating a high concentration of cinnamaldehyde. Ensure the moisture content is below 13.5% to prevent mold during transit. Buyers should distinguish between Cassia Lignea (Chinese Cinnamon) and other varieties, focusing on the thickness of the bark (ideally 2mm-4mm for split grades) and the absence of 'white fungus' or excessive 'scrap' material.