From a reader:
I wanted to know if it is permissible to buy relics. I know that Canon Law says that it is absolutely wrong to sell them. But what about buying them? Also, how do I go about confirming the authenticity of the relic. I feel that the documentation can be easily forged.
It is not permissible to sell relics, which is a terrible sin and sacrilege. It is similarly sinful to traffic in relics by buying them for anything other than the motive of saving them from profanation. It is permissible to buy a relic to "rescue" it from mistreatment or other unworthy purposes.
When a person seeks to obtain a relic, from an approved source such as the Vicariate of Rome of the HQ of a religious order or institute or, perhaps, a postulator of a cause, there can often be an expense involved. The expense is not for the relic, but for the purchase of the reliquary, the preparation of the relic, a document, etc.
Again, buying and selling relics, trafficking in relics, is thoroughly wicked and deserves our deepest pity-filled contempt.
It is laudable, however, to "rescue" relics from mistreatment.
As far as documentation is concerned, it can be difficult today to obtain documents even from approved sources for relics. This is especially the case with relics of saint from the distant past. However, reliquaries when opened usually reveal a waxen seal, embossed by the entity that handled the relics. It could be possible to hunt down the source of the relic, which can help to authenticate that it was prepared under the aegis of Church authority.
Some might argue that by "rescuing" a relic, you create a market for them, inspiring the unethical to do sacrilegious things for profit.
If you are in doubt, bring your concern to your local bishop and ask for advice. If that does not produce swift results, you can write to the Congregation for Causes of Saints for advice, sending a copy of your correspondence.