I've been experimenting a little bit with manipulating the sprites, and tested this.
On the left is Item 28 - the Lesser Healing Potion. In the middle is the one in the pack. On the right is a revised sprite.
View attachment 139446 View attachment 139447 View attachment 139448 (hooray for transparency fails)
In the middle sprite, I did what I've been doing other sprites - picking one color out of their palette and making the sprite look monotonous as always.
On the right, however, I took the color of the bottleneck's outline and brought it all the way around - and made the original outline into a small stripe across the bottle. Which do you like better? Let me know!