The premium label when it comes to green tea is completely subjective. Green teas are so diverse, even tea experts and connoisseurs who know how to find and choose premium or high-quality teas cannot agree on which tea deserves the title of "best green tea". You can view here https://healtheries.co.nz/products/tea for premium quality green tea.
However, there are still some things you as a buyer can do to educate your purchases by visiting this website. You are probably looking for the highest quality green tea and you want to pay the lowest price for it.
Many people are just accustomed to drinking tea packaged in a teabag. While there are several high-quality teas in sachets, most of the best teas are offered only in a form of loose-leafs.
By buying loose leaf tea, you are primarily paying for the actual process of producing the leaves, and therefore primarily for the quality of the leaves themselves as well as the taste and aroma of the finished tea.
Any company that takes tea seriously and legally deserves the "Premium" label will offer and most likely focus on loose leaf teas. Many of the best companies that can buy green tea sell only loose leaves.
Green tea was often a mixture of teas from different vintages, different regions, and varieties. Each of these creates a unique aroma in the cup.