Check the visible parts of the faucet, including the upper part of the stem and the curved piece that releases water. The faucet might have Friedrich Grohe or simply Grohe engraved into one of the top parts of the faucet.
Examine the bottom of the faucet stem. The stem is the straight metal piece that slides through a hole in your sink. An authentic Grohe faucet lists the manufacturer’s name on the faucet. You should see Friedrich Grohe or Grohe in capital letters on the stem.
Unscrew the screws and bolts holding the sink in place with a screwdriver and wrench. Check each part, looking for the Grohe name in capital letters. If it is authentic, you should see the company name somewhere on the piece.
Visit the Grohe website and compare your model against the current models available from the company. Even if the company no longer makes your exact model, you should notice similarities in terms of shape and design.
Contact Grohe directly and ask about your particular model. For replacement parts or technical support, the company requires a model name and other identifying marks. Explain that you cannot find any identifying marks, but want to verify the authenticity of your faucet.