The relics were collected over many year by Lama Zopa Rinpoche, the spiritual founder of the Maitreya Heart Shrine Relic Tour, organisers of the exposition.
The relics will be enshrined in a 150 ft bronze statue of Maitreya Buddha to be built in Bodhgaya. According to Buddhist scriptures, Maitreya will be the next Buddha to bring teachings of love and kindness to the world.
Sikkim Chief Minister Pawan Chamling lighted the lamp and took part in the ceremony initiated by Tshuklakhang monks.
Donations collected from the relics' tour of the world will be used for the construction of the statue.
The exposition of relics which arrived in Sikkim after touring 66 countries, would be open for the public till December 1.
The opening ceremony was attended by state assembly Speaker KT Gyaltsen, cabinet members, Chief Secretary R Ongmu among others.