When sourcing glass bowl vases, you must distinguish between hand-blown and machine-made glass. Hand-blown glass offers unique artistic value and thicker walls, but may have slight variations in size. Machine-made glass provides high consistency and lower unit costs, ideal for high-volume retail. Ensure the material is high-borosilicate glass if heat resistance is required, or soda-lime glass for standard decorative use. Check for clarity and the absence of bubbles or streaks, which are indicators of high-quality raw materials.