Seller verification

We only work with selected sellers, who meet the standards we set.

Verification of offers

Each offer is verified by a Clemens employee or an external expert.

Verification in databases maintained by the MKiDN

All items added by sellers are verified in the databases of stolen and exported objects run by the Ministry of Culture and National Heritage.

Form for reporting violations and irregularities

Each offer includes a violation reporting form and irregularities by users.

Transaction and payment security

We provide secure, encrypted payment transactions.

Confidentiality and protection of personal data

We ensure confidentiality and protection of personal data.



Security aspects in online transactions

Lack of trust in online transactions is one of the most significant limitations to the development of online commerce. The market for art, antiques, collectibles and luxury goods is currently the most dynamically changing capital market in the world. In the face of numerous crises on financial markets and a drastic decline in trust in traditional forms of investment, a sign of modern times is the dynamic development of turnover on these markets. These markets have become a kind of vaccine against the diseases of the financial market, hence the increase in demand from both connoisseurs and entities looking for alternative forms of capital involvement. Works of art, antiques, luxury goods or collectibles can be a very good investment of capital and an investment with a high rate of return, but only if the investor purchases authentic objects that have real market value.

In recent years, there has been a dynamic development of online trade. Buying goods online is very convenient. Nevertheless, it should be remembered that purchasing works of art, antiques, jewelry, collectibles and luxury goods using publicly available and very popular online auction and advertising websites is characterized by a relatively high degree of risk due to the possibility of becoming a victim of fraud. Virtually anyone can be a seller there, and these websites generally do not sufficiently verify the reliability of these sellers. Due to the lack of qualified and experienced staff, as well as due to the very large number of offers, objects are usually not verified in terms of authenticity, origin, condition, real value, etc. A large percentage of deceived people are not aware of this fact, therefore dishonest Sellers may continue to operate. All this undermines customer confidence in purchasing this type of items online.

These types of goods should be purchased from Sellers who are specialized and have appropriate knowledge and extensive experience in trading this type of products. Usually, these are recognized art galleries, art salons, auction houses, antique shops, experienced jewelers, numismatic salons, specialized boutiques and narrowly specialized dealers and specialist stores which, before putting a given object up for sale, check it by visually verifying it and seeking knowledge from experts whose main task is to trace provenance and verify attribution. Clemens brings together the best Sellers who meet our criteria and the standards we set. In addition to presenting sales offers, Clemens ensures the safety and proper conduct of sales transactions and protects the interests of both Buyers and Sellers.

Safety rules applied at Clemens

Seller Verification

Clemens cooperates only with selected Sellers who meet our quality standards and guarantee the proper conduct of the sales transaction. When selecting Sellers, we are guided by strictly defined criteria, which can be found on the Participation Criteria for Sellers page.

Guidelines for the description of the offer

When preparing an offer description, each Seller is obliged to follow the guidelines regarding the offer description, posted on the Rules for creating an Offer description page.

Pricing Guidelines

When setting the price of an item, each Seller is obliged to follow the price guidelines posted on the Rules for creating an Offer description page.

Photo Guidelines

When photographing an item, each Seller is obliged to comply with the requirements regarding photos posted on the Rules for creating an Offer description page.

Prohibited goods

Sellers cannot offer goods on the Clemens Website that are on the Prohibited Goods list.

Verification of offers

Each newly added offer is verified by a Clemens employee or an external expert (so-called Moderator) who has applicable knowledge and experience in a given field. The moderator is obliged to verify whether a given offer complies with the regulations, in particular with the rules for creating an offer description, and whether the item meets the guidelines given in the internal document entitled: "Quality Assurance Program". The Moderator makes decisions based on his knowledge and experience and on the information provided by the Seller. The moderator also has the right to edit descriptions, photos and parameters of offers, in accordance with the principles described in the regulations. The moderator does not interfere with the substantive content of offers or prices, but if there are any doubts as to the reliability of the description of a given offer, or the compliance of the item with the description, etc., he may suspend the publication of a given sales offer until the matter is clarified. Clemens cooperates only with recognized experts in a given field who support us substantively in verifying and approving objects for publication.

Quality assurance program

In order to ensure the appropriate quality level of items offered on the Clemens website, a special internal document has been prepared, which contains a detailed set of criteria and guidelines regarding the qualitative, aesthetic and assortment features of Items that may be allowed for sale. on the Clemens website. When making a decision regarding the publication of an offer, each Moderator is obliged to verify whether a given item meets all the criteria specified in the document entitled: "Quality Assurance Program".

Verification in databases maintained by the Ministry of Culture and National Heritage

All items added by sellers are automatically verified in the databases maintained by the Ministry of Culture and National Heritage, i.e. the Catalog of War Losses and the National List of Monuments Stolen or Illegally Taken Abroad.

Private sale

When adding a new offer, the seller can mark it as the so-called private sale. In such a situation, access to this offer is limited only to users who have purchased a special subscription and therefore have appropriate access rights. Private sale offers are located in a separate and hidden part of the website, which is secured with encryption algorithms and passwords, so it is not visible in the public online space. No web browser robot is able to enter this strictly protected part of the website and index the content there. Sellers can therefore be sure that their private sale offers will not appear in Google or other search engines. Private sale offers are subject to the same verification rules as all other offers.

For detailed information on private sales, please visit the Private Sales website.

Form for reporting violations and irregularities

To increase the level of security on the website, each offer includes a form for reporting violations and irregularities. This form is intended for Users who have reasonable suspicions or have information that a given product comes from theft or crime, violates applicable law or the rights of third parties, is on the list of prohibited goods, is inconsistent with the description or otherwise violates the Clemens regulations. Personal data and information provided in this form are treated as confidential and are not visible to unauthorized persons. This data is not made available to the Seller, unless the User reporting the violation gives written consent to make this data available to the Seller. If the Clemens Administrator has justified doubts, he may decide to suspend the publication of such an offer until all doubts are clarified with the Seller.

Auction security

Dutch auctions used at Clemens are completely safe. Even though the price is automatically reduced during the Dutch auction, there is no risk of selling the item for an amount that is disproportionate to its value, because the seller always sets the minimum price, i.e. the lowest price at which he agrees to sell the item. Moreover, Dutch auctions are resistant to unfair auction practices that may be used in traditional auctions.

For more information, please visit the Dutch Auctions page.

Transaction and payment security

User data while browsing the website is safe. The guarantee is an SSL connection encrypted with a 128-bit key, certified by the recognized organization DigiCert Inc., which ensures, among others: confidentiality of data transmission. The browser connects to the website using SSL each time:

  • when logging into your account or registering;
  • when placing an order, bidding, submitting price offers and providing your personal data;
  • when you choose the online payment option and make a transfer or credit card payment. All this data is safe.

In the situations described above (logging in, placing an order, payment, etc.), the Clemens website address in the browser's address bar will be preceded by the inscription https - the letter s means a secure connection. Additionally, a green lock icon will appear next to the address.

Data and content security

The Clemens platform uses, among others: secure communication encryption protocol (SSL), and personal data is stored on modern and secured servers. We have implemented pseudonymization, data encryption and access controls, thanks to which we minimize the effects of a possible data security breach. Moreover, in order to protect the content and hinder the illegal copying of text, graphics and photos, we have introduced a context menu blocker.

Confidentiality and protection of personal data

We know how important it is to maintain confidentiality, discretion and protection of customers' personal data in the trade of works of art, antiques, collectibles, jewelry and luxury goods. In our activities, we bear in mind the fact that many buyers of this type of goods do not want their personal data, or data on transactions concluded by them, to be made public in any form or transferred to third parties. As part of the adopted Privacy Policy, Clemens does not transfer Users' personal data or any information about transactions concluded by them to third parties without the consent of the Users concerned. Personal data is treated as confidential and is not visible to unauthorized persons. Personal data are processed to the extent and for the purpose necessary to establish and shape the content of the contract, change or terminate it and properly perform the services provided within Clemens. The processing of personal data does not violate the rights and freedoms of the data subject. The Buyer's personal data is transferred to the Seller only at the time of purchasing the item. We provide only the data that is absolutely necessary to complete the transaction, i.e. name and surname, e-mail, delivery address and telephone number, and if it is necessary to issue an invoice - company details. Transactions on the Clemens platform are conducted in such a way as not to disclose to other Users or third parties data on the basis of which the buyer and the Seller of a given product can be identified.

Detailed information about Clemens' privacy policy can be found on the Privacy Policy page.