Magnifying glass in D&D 5e costs 100 gp.
This lens allows a closer look at small objects. It is also useful as a substitute for flint and steel when starting fires. Lighting a fire with a magnifying glass requires light as bright as sunlight to focus, tinder to ignite, and about 5 minutes for the fire to ignite.
A magnifying glass grants advantage on any ability check made to appraise or inspect an item that is small or highly detailed.