According to Official Guinness Records,
The largest diabolo measured 1.3 m (4 ft 3 in) in diameter and was manufactured by Wang Yueqiu (China) and displayed on the set of Zheng Da Zong Yi - Guinness World Records Special in Beijing, China, on 20 September 2007.Wang Yueqiu spun the diabolo on the show to demonstrate its working order.
For a complete list of 2007 records, please visit 2007 Guinness Records in China.