This compares with $14.7 billion in the same period last year.
The labour-intensive sector contributes about 14 per cent to the country's overall export. The drop in shipments is mainly due to negative growth in export of gold jewellery, gold medallions and coins and rough diamonds.
Gold jewellery shipments during the period declined about 8 per cent to $1.30 billion. Similarly, export of gold medallions and coins and rough diamonds contracted by 18 per cent and 5 per cent, respectively.
However, silver jewellery export went up to $2 billion in April-August 2017-18, from $1.67 billion a year ago.
Export of cut and polished diamonds reported a growth of just 0.51 per cent.
India's main export destinations are Europe, Japan, China and the US.
According to GJEPC, the sector is facing issues related to compliance of the Goods and Services tax (GST). It had demanded exemption from Integrated GST (IGST) on the procurement of precious metals from nominated agencies for the purpose of manufacturing and export of jewellery.
According to the data, import of rough diamonds rose by 8.84 per cent to $7.7 billion in April-August.
Import of gold bars, however, slid 38.5 per cent to $1.26 billion.