Diamond Kinesis Pipe is a type of Kinesis Pipe added by BuildCraft for energy transmission with a maximum of 10,240 RF/t. Thus it has a higher transmission rate than the Cobblestone, Stone, Golden and Quartz Kinesis Pipe, but for that the crafting is extremely expensive. If the maximum energy input is reached, any more will make the energy "wire" inside the pipe to turn red indicating a bottleneck which will only allow the amount of energy the pipe can handle.
The Diamond Kinesis Pipe was added by Buildcraft v.3.70+ and has the same function as energy transport pipe, but was used to transport Minecraft Joules (MJ) until version 6.1.1 of BuildCraft. Since version 6.1.2 the energy system MJ was replaced by Redstone Flux. Below this version it has a maximum transmission of 1024 MJ without energy lose over distance and the same recipe as now.