Paul Sheeran does not just sell jewellery and watches for a living.  The founder of the eponymous jewellery retailing business in the heart of Dublin sells far more than that. He sells luxury. He sells a lifestyle. Crucially, he sells a brand – both his brand and the brand of the high-value watches that he stocks.  I have known Paul for decades, back to when we were both in our teens. I remember being surprised when he went off to study horology and when he opened his first store in the suburbs. But I have not been surprised by his…