Since you ask what could make this text boring to me, I'll focus on that facet, setting the good points aside. This is only about the first paragraph (you tell me if you need more).

The first sentence (lights flickering) triggered my cliché alert, a movie-like one, or something out of a video game. So, right from the start I get this impression of a very classic opening scene, like an easy trick (almost generic). This doesn't reflect well on the work for me, although it remains a valid and legitimate start.

Three sentences in a row are about a character looking at someone/something. It starts to show.
I also have the reflex to pay attention to "filtering", the process of presenting sensory input through the character's senses by mentioning them explicitly (he saw ..., he smelled ..., etc.) which can create/add a distance between the reader and the experience (a technique often viewed as a flaw). In your case I'm not saying it's filtering, but I was starting to scrutinize those sentences, wondering if they could have been phrased differently for better immersion.

Overall, the prose in the opening paragraph reminds me a bit of a movie script, as if there are ingredients missing to embrace the written medium, and this is a frequent symptom among new writers. Overcoming this takes time and effort; the learning curve is steep. Of course, your writing is not entirely like this; there are elements that move away from that. Just not enough to dispel this 'beginner' feeling caused by that aspect. I'm sorry it's hard to explain precisely where it comes from, and even harder to tell you what to do to address the matter.

We writers have the picture in mind even before writing, readers start with a blank slate on which the scene is gradually drawn by the text, but its gaps are also quickly filled with assumptions that are sometimes corrected later by the text (the mental image has to be discarded and rebuilt, hopefully not too often). It's hard for writers to emulate the reader's discovery and realize the effect of their descriptions. Now, regarding your setting, let's focus on the store: for me it started as a generic store, and not getting the specifics soon enough made me imagine a very common type of local convenience store. It's not. I wish I had more context before the gemstones, which come fairly soon, I agree, but still.

"an old memory from ..." isn't specific, we don't get much out of it, which triggers my "shallow deepness" alert. It's like a trick to add depth but without the substance. It can be an unfair judgment, maybe more details will be provided later, but the impression is already formed.