What is a guarantee of authenticity?
Buying ancient art and artefacts is a matter of trust. Thus, every time when you want to buy an artefact, the following question might arise: Is the item genuinely ancient? What do statements such as “guaranteed genuine” or “guarantee of authenticity” mean when acquiring antiquities?
A “guarantee of authenticity” grants you as a customer the right to return an allegedly ancient artefact, in case serious doubts arise regarding the authenticity of the item. But be mindful, there are some "black sheep" out there. Sometimes, the most blatant fakes come with the most colourful "certificates of authenticity".
Nevertheless, ask your gallery for a non-expiring guarantee of authenticity for all purchased items. Reputable sellers will not hesitate to grant you and every customer such an assurance.
How can someone tell something is authentic?
Purchasing genuine antiquities from the classical era is a major challenge for collectors. This is the case for over a century. The so-called "Grand Tour" souvenirs from late 19th century flooded the international art market not only with genuine antiquities but also with their fake counterparts, making it difficult for non-experts and even for experts to distinguish between them. Nowadays, archaeometrical analyses can be applied to distinguish between a well-made reproduction and the original. However, an experienced eye is remaining crucial and more important than ever.
Start small, choose a certain group of items and learn about them. Look at real specimen in museums and in literature. If you encounter a suspected fake, study it. Only by experience can you learn. As you will not become an expert right at the start and you can never be knowledgeable about an arbitrarily wide range of items: choose a reliable partner to support you with his expertise! This could be a trusted antiquities dealer or a curator from a public museum, someone who is seeing first hand a wide range of classical antiquities - real and fake alike.