If you want a spec that actually predicts how the matcha will taste and feel, look for the harvest date. Freshness is king. Matcha that was stone-ground this year will have a vibrant color and a sweet, umami flavor. Older matcha—even if it's sealed—turns dull and loses that bright aroma.

Here's a simple checklist:

• Harvest date: Look for something within the last 6-12 months. If it's not printed, ask the seller.
• Origin: Single-origin (like Uji or Kagoshima) is usually a safe bet for quality, but not a guarantee.
• Stone-ground vs. machine-ground: Stone-ground is finer and has a smoother texture, but machine-ground is fine for most uses.
• Ingredient list: It should be just one ingredient: green tea leaves. If there's sugar or anything else, it's not pure matcha.

That's the spec that matters. The rest is noise.