Like all manufacturers of glass we are unable to offer a guarantee on glass due to the very nature of the material. If you receive a new product and the glass is broken we will replace this for you as long as the damage is reported within 5 working days of receipt as shown on your tracking information. Most glass products will last for many years however we would also suggest buying a replacement when buying a product as it is common for breakages to occur and this will reduce your shipping costs if this does happen. If you sign up for our newsletter you get a 10% discount on spares (excluding grinder burrs). You can find this on the bottom right of every page and your follow up email will include a discount code.