Ultimately, the type of gemstone you choose for a ring or any type of jewelry, comes down to personal preference. There are however, some general tips for choosing gemstones:

1. Consider the color: Gemstones come in a wide range of colors, so think about what colors you like and what will complement your skin tone and wardrobe.
2. Consider the meaning: Many gemstones are believed to have certain meanings or properties. For example, amethyst is associated with calming energy, while garnet is associated with love and devotion. Consider the meanings behind different gemstones and choose one that resonates with you.
3. Consider the durability: Different gemstones have different levels of hardness and durability, which can impact how well they will hold up over time. If you're planning on wearing a gemstone ring everyday or for special occassions, choose a gemstone that is durable enough to withstand the situation.
4. Consider the setting: The setting can also impact the appearance of the gemstone, so consider what type of setting will best showcase the gemstone's color and brilliance.
5. Consider the price: Gemstones can vary widely in price, so consider your budget and what you're willing to spend. Some gemstones, such as diamonds and sapphires, are typically more expensive than others.

Gemstones aren't necessarily "better or worse" than diamonds, especially when used in rings, but there are some distinct differences:

1. Cost: Gemstones can be less expensive than diamonds, especially if you're looking at rarer or higher-quality diamonds. So, if cost is a concern, a gemstone may be a better option for you.
2. Variety: Gemstones come in a wide range of colors and varieties, whereas diamonds are typically colorless or near-colorless. If you want a unique and colorful piece of jewelry, a gemstone may be a better choice for you.
3. Durability: Diamonds are one of the hardest substances on Earth and are very durable, making them an ideal choice for engagement rings and other jewelry that will be worn every day. Some gemstones, like sapphires and rubies, are also quite durable, while others may be more prone to chipping or scratching.
4. Brilliance: Diamonds are known for their brilliant sparkle, which is due to their high refractive index. Some gemstones, like sapphires and emeralds, may not have the same level of brilliance as diamonds.

Whether gemstone rings hold their value depends on a variety of factors, including the rarity, quality, and demand for the particular gemstone. Some gemstones, such sapphires and rubies, have historically held their value well and may even increase in value over time.

However, other gemstones may not hold their value as well. For example, some gemstones like citrines and amethyst may be less rare or less popular, making them less valuable. Additionally, the value of a gemstone can be impacted by factors such as the cut, clarity, and color of the stone, as well as the condition of the jewelry setting.