The diameter of a bamboo skewer can vary depending on its purpose and usage. Typically, bamboo skewers have a diameter ranging from 2mm to 6mm. Thinner skewers with a diameter of around 2mm to 3mm are commonly used for skewering smaller food items such as fruits, vegetables, and shrimp. Thicker skewers with a diameter of around 4mm to 6mm are suitable for skewering larger pieces of meat or for more heavy-duty grilling or barbecue applications. It's important to choose the appropriate diameter of bamboo skewer based on the size and weight of the food you plan to skewer to ensure proper cooking and presentation.