A Mani Jewel (Chinese: 摩尼珠; pinyin: móní zhū; Japanese: mani ju) refers to any of various jewels mentioned in Buddhist literature as either metaphors for several concepts in Buddhist philosophy or as mythical relics. The word mani is simply Sanskrit and Pali for "jewel", so the phrase "Mani Jewel" is in one sense redundant. However, the Mani Jewel metaphors were significantly expanded in Chinese language texts in which it was also called by essentially the same redundant name móní zhū, where the first two characters (摩尼, móní) are the transcription of mani and the third character (珠) is its Chinese translation, "jewel". The English phrase "Mani Jewel" is thus in essence a translation of the Chinese term. The use of the Mani Jewel in Buddhist literature includes various magical relics such as the wish-fulfilling cintamani as well as metaphorical devices to illustrate several ideas such as Buddha-nature and Śūnyatā.
The Mani Jewel makes its first appearance in the Pali Nikāyas where it is mentioned as one of the seven treasures owned by a "wheel-turning king". The Mahasudhassana Sutta in the Digha Nikaya describes the Mani Jewel as follows:
“It was a beryl, pure, excellent, well-cut into eight facets, clear, bright, unflawed, perfect in every respect. The luster of this Jewel-Treasure radiated for an entire yojana round about.
The Mani Jewel in this text serves as the source of virtue and good governance for the king. Without it he would lose his throne.
Later texts describe the Mani Jewel differently. One version is the Cintamani or wish-fulfilling jewel. It was said to be originally owned by the God Indra, but it fell to the earth during a war with the Asuras, allowing whoever possess it to have their wishes granted. Depictions of the Bodhisattvas Ksitigarbha and Avalokiteshvara sometimes show them holding this Cintamani, indicating their ability to fulfill the wishes of sentient beings.