The names and contact detail of Best Institutes or Centers for Gemology in India as your nephew wants to take admission in it are as follows:

Sinhgad School of Gemmology and Jewellery Designing
19/15, Khilare Marg Next to Hotel Kalinga / Near Sharada Centre Erandawane, Nal Stop, Karve Rd , Pune (Pune Dist.) – 411004

Indian Institute of Jewellery (I.I.J.)
Modern Centre, Sane Guruji Marg, Mahalaxmi , Mumbai (Mumbai Dist.) – 400011

St. Xaviers College,
5, Mahapalika Marg , Mumbai (Mumbai Dist.) – 400001

Creations - The School of Design and Technology
Lunkad Villa, Ashok Path, Law College Road, Opp. Cafe Coffee Day , Pune (Pune Dist.) – 411004

International Institute of Gemological Sciences
Plot No.1, 1st Floor, Pandav Nagar, Opp. Mother Dairy , New Delhi (Delhi) – 110092

Solitaire Diamond Institute (SDI)
#62/A,1st floor,40th Cross,6th Main,5th Block,Jayanagar , Bangalore (Bengaluru Dist.) – 560041

Arch Academy of Design
Plot No. 9, Govind Marg, Malviya Nagar Institutional Area, Malviya Nagar , Jaipur (Jaipur Dist.) – 302017

DNADS
#4 Sri Rama Plaza, DVG Road, Gandhi Bazaar Circle, Basavanagudi , Bangalore (Bengaluru Dist.) – 560004

P.D Institute of Gem Stone Manufacturing and Management
344, Bees Dukan, Near Seva Sadan, Adarsh Nagar , Jaipur (Jaipur Dist.) – 302004

Aesera Academy of Design
144/74, Eskay Building, 3rd floor, Greams Road, Thousand Lights , Chennai (Chennai Dist.) – 600006

Vogue Institute of Fashion Technology
Football Stadium Complex, Diagonally Opp. Garuda Mall, Off MG Road , Bangalore (Bengaluru Dist.) – 560025

Arihant Diamond Institute
Ground Floor, Hare Krishna Complex, Dalagiya Mahollo, Mahidhar Pura , Surat (Surat Dist.) – 395003

International Gemological Institute
404, Mani Mahal, 11/21 Mathew Road, Opera House , Mumbai (Mumbai Dist.) – 400004

J.K. Diamonds Institute of Gems and Jewelry
506, Parekh Market, 39, Kennedy Bridge, Opera House , Mumbai (Mumbai Dist.) – 400004