Step 1: Calculate the mass of diamond per cubic meter.
The bulk density is given as 2.5 g/cc, and we convert this to kg/m³.
Since \(1 \, \text{g/cc} = 1000 \, \text{kg/m}^3\), we have:
\[
\text{Bulk density} = 2.5 \, \text{g/cc} = 2500 \, \text{kg/m}^3
\]
Step 2: Determine how many carats are there in 1 metric ton.
1 metric ton = 1000 kg.
Since the grade is 100 carats per metric ton, there are:
\[
100 \, \text{carats} \, \text{per} \, 1000 \, \text{kg}.
\]
Step 3: Calculate the number of carats per cubic meter.
The number of carats per cubic meter is:
\[
\frac{2500 \, \text{kg/m}^3}{1000} \times 100 = 250 \, \text{carats/m}^3
\]
Step 4: Find the number of diamond crystals per cubic meter.
Since each diamond crystal is 1 carat, the number of crystals per cubic meter is the same as the number of carats:
\[
\boxed{250}
\]
Final Answer:
\[
\boxed{250}
\]