The Ketaka Gem (Tib. ནོར་བུ་ཀེ་ཏ་ཀ་, Norbu Ketaka, Wyl. nor bu ke ta ka), a commentary on the ninth chapter of the Bodhicharyavatara written by Mipham Rinpoche, based on the teachings of Patrul Rinpoche. It was composed in 1878, when Mipham Rinpoche was 32.
Lhobpon Rechunpa said:
- From the emanation of Lokeshvara, Dza Paltrul Rinpoche, [Mipham Rinpoche] received the Wisdom Chapter of the Bodhicharyavatara in only five days. Based on this, he wrote the commentary on the Wisdom Chapter known as the She Drel Keta Ka. 
Mipham Rinpoche himself said:
- “When I was young, I was present when many accomplished, learned lamas gave Dharma teachings, but I only seriously studied Dza Patrul Rinpoche’s teachings on the Wisdom Chapter of the Bodhicharyavatara. Later, in dependence on the kindness of my venerable lama and Manjushri, no difficulties with study ever arose for me.”
The commentary provoked several refutations from Gelugpa scholars, especially Pariwa Lobzang Rabsal and Drakkar Lobzang Palden Tendzin Nyendrak. Mipham Rinpoche wrote two lengthy responses to their objections: Clear Logic Illuminating Reality (rigs lam rab gsal de nyid snang byed) in response to Pariwa Lobzang Rabsal, and Response to Objections: The Light of the Sun (rgal lan nyin byed snang ba) to Drakkar Lobzang Palden Tendzin Nyendrak.
- Ketaka is a gemstone that is said to be able to purify dirty water.
- Biography of Jamgon Ju Mipham Rinpoche Namgyal Gyatso by Lhobpon Rechungpa and Eric Forgeng (see rangjung.com)
- See Nectar of Manjushri's Speech, Padmakara Translations, Nov 2007, page 250
- E. Gene Smith, 'Mi Pham and the Philosophical Controversies of the Nineteenth Century', in Among Tibetan Texts, Wisdom, 2001, ISBN 978-0861711796