Suspicious Lamps are a type of redstone lamp which gives off no light, but can disable mob spawners and prevent low light mob spawning. These lamps do not support colored lighting and also have a nice little advancement when placing them.
To craft a suspicious lamp, you will need:
1x Nether Quartz 1x Minecraft Redstone Lamp
Place the above ingredients in the middle row of your crafting table in the following order from the left: Nether Quartz, Redstone Lamp (or see image above)
Suspicious lamps require a redstone signal to work. You will see a texture change when the lamp is powered.